Traffic management in distributed wireless networks

ABSTRACT

Wireless networks and devices are ubiquitous today. For service providers to offer customers QoS and Service Level Agreements (SLAs) means in part providing resilient connectivity of wireless devices with good signal strength, good Signal to Noise and Interference Ratio (SNIR), and adequate useable bandwidth. Doing so requires that devices transmitting and receiving packets use over-the-air bandwidth efficiently and manage over-the-air congestion. According to embodiments of the invention QoS measurements and controls are incorporated only in the network (i.e. APs or controllers) and therefore QoS and SLAs can be achieved with all deployed client stations versus standards based approaches that require additional capabilities in network nodes, client stations and in most cases modifications to the applications. SLAs can be provided exploiting embodiments of the invention for traffic prioritization, capacity improvements through load distribution, and adjacent channel interference mitigation discretely or in combination with standards based mechanisms.

FIELD OF THE INVENTION

This invention relates to wireless networks and more specifically tomanaging access, maximizing carried network traffic and ensuring qualityof service within wireless networks.

BACKGROUND OF THE INVENTION

Wireless communication systems are today well known in the art havingfundamentally changed how consumers, advertisers, and enterprisesinteract, communicate, exchange, store, and utilize information througha variety of formats including text, electronic mail, video, multimedia,and plain-old-telephone-service (POTS) as well as through a variety ofmobile wireless devices from cellular telephones (cellphones), personaldigital assistants (PDAs), laptops, tablet PCs, portable multimediaplayers, and portable gaming consoles. The Technology, Media andTelecommunications (TMT) business has grown in the past 10 years withthe widespread deployment of wireless devices, personal computers,Internet, and broadband networks to represent a value chain of over $3trillion worldwide, including content providers, advertisers,telecommunications companies and electronics suppliers (White PaperWireless Social Networking from iSuppli, July 2008).

In the next decade wireless social networking products alone(applications, components, and advertising) will generate more than $2.5trillion in revenue by 2020, according to iSuppli (Press Release, Jun.4, 2008 http://www.isuppli.com/NewsDetail.aspx?ID=12930). During thistimeframe it is anticipated that mobile devices, such as cellulartelephones, smart phones, personal digital assistants (PDA), will becomethe primary channel for viewing content from or accessing the Internet(World Wide Web) and that many applications such as social networking,email, and financial transactions will have moved substantially into thewireless realm providing the degree and type of ubiquitous connectionthat consumers demand. At the same time it is anticipated that thisevolution will be accompanied by the creation of a new generation ofapplications that will greatly expand the appeal, utility, andcapabilities of mobile wireless devices.

Today, with a global population of approximately 6.9 billion there areestimated to be 5 billion active cellphone connections globally (see BBCJul. 18, 2010 new report http://www.bbc.co.uk/news/10569081 citingmarket analysts Wireless Intelligence), which is approximately 3 timesthe number of computers globally. More than a billion cellularconnections were added in the past 18 months, with China and Indiadominating these new connections with approximately 830 million and 706million users respectively. However, the vast majority of thesecellphone connections are currently “low functionality” wireless mobilecellphones and PDAs with only approximately 450 million mobile Internetusers in 2009, about 10% of overall users (International DataCorporation cited in PC Worldhttp://www.pcworld.com/article/184127/idc_(—)1_billion_mobile_devices_will_go_online_by_(—)2013.html“Worldwide Converged Mobile Device 2009-2013 Forecast Update” December2009).

However, with the evolution of smartphones, Internet-capable cellphonesand PDAs, tablet PCs then as these devices become more affordable thesedevices will increase, to approximately 1 billion in 2013, beingdominated by North America, Europe and Japan, and thereafterincreasingly penetrating markets such as China and India. Accordingly,the average user will increasingly consume bandwidth and networkresources as well as potentially accessing multiple servicessimultaneously, for example VoIP and Internet access for streamingmultimedia or accessing information. Accordingly, for telecommunicationservice providers managing congestion as well as access for users is,and increasingly will be, an important issue. This will be furtherexacerbated as guaranteed network access is required, either to extendexisting wired service level agreements (SLAs) for enterprises towireless networks or where critical applications such as those relatingto financial, security or medical applications are executed through themobile devices.

Generally, wireless telecommunications networks comprise communicationstations that transmit and receive wireless communication signalsbetween each other. Depending upon the type of system, thesecommunication stations typically are one of two types of wirelesstransmit/receive units (WTRUs): one type is the Access Point (AP) orbase station, the other is the station (STA) or subscriber unit, whichmay or may not be mobile.

The term AP as used herein includes, but is not limited to, a basestation, an Access Point, Node B, site controller, wireless router orother interfacing device or WTRU in a wireless environment, thatprovides other WTRUs with wireless access to a network with which the APis associated. The AP may be associated with wired and/or wirelessnetwork(s). The term STA as used herein includes, but is not limited to,a station WTRU, user equipment, a mobile station, fixed or mobilesubscriber unit, pager, or any other type of device capable of operatingin a wireless environment and accessing an AP to obtain access to thenetwork. Such STAs can include personal communication devices, such ascellular telephones, video phones, so-called Internet ready phones thathave network connections. In addition, STAs can include portablepersonal computing and communication devices, such as smartphone, PDAs,netbook computers/laptop computers/tablet PCs etc. with wireless modemsthat have similar network capabilities, multimedia players, and gamingconsoles. STAs that are portable or can otherwise change location arereferred to as mobile units. In some instances, STAs may also provide APfunctionality by operating at two telecommunication standardssimultaneously.

Typically, a network of APs is provided wherein each AP is capable ofconducting concurrent wireless communications with appropriatelyconfigured STAs, as well as other multiple appropriately configured APs.Some STAs may alternatively be configured to conduct wirelesscommunications directly between each other, i.e., without being relayedthrough a network via an AP. This is commonly called peer-to-peerwireless communications. Where a STA is configured to communicatedirectly with other STAs it may itself also be configured as andfunction as an AP. STAs can be configured for use in multiple networks,including for example those with both network and peer-to-peercommunications capabilities as well as supporting single or multiplebasic service sets.

One type of wireless system, called a wireless local area network(WLAN), can be configured to conduct wireless communications with STAsequipped with WLAN modems that are also able to conduct peer-to-peercommunications with similarly equipped STAs. It should be noted that inIEEE standards an STA is typically associated as being the WLAN modemrather than a station comprising such a modem. Currently, WLAN modemsare being integrated into many traditional communicating and computingdevices by manufacturers including, but not limited to, cellular phones,personal digital assistants, and laptop computers. Popular WLANenvironments with one or more WLAN APs are generally those constructedaccording to one or more of the IEEE 802 family of wireless standards.Access to these networks usually requires user authenticationprocedures. Protocols for such systems exist at multiple levels ofmaturity including those that have been ratified as standards and arecommercially deployed, those that are being formalized for ratificationand may or may not be commercially deployed, those that are proposed andare being refined by industry prior to commercial release/ratification,and legacy/obsolete standards. As such IEEE 802 is one such family ofstandards, and multiple standards are active simultaneously andextensively globally.

A basic service set (BSS) is the basic building block of an IEEE 802.11WLAN, which comprises WTRU STAs. A set of STAs that can talk to eachother can form a BSS. A single-cell wireless LAN using the IEEE 802.11Wireless LAN Standard therefore is a Basic Service Set (BSS) network.Multiple BSSs are interconnected through an architectural componentcalled a distribution system (DS), to form an extended service set(ESS). An ESS satisfies the need for large coverage networks ofarbitrary size and complexity to form the wireless infrastructure thatconsumers take for granted.

The IEEE 802.11 Wireless LAN Standard is published in multiple partsincluding:

-   -   IEEE 80.211-1997 (802.11 legacy) with spread-spectrum        transmission at 1-2 Mb/s at 900 MHz or 2.4 GHz;    -   IEEE 802.11a-1999 for unlicensed portions of the radio spectrum,        usually either in the 2.4 GHz Industrial, Scientific, and        Medical (ISM) band or the 5 GHz Unlicensed-National Information        Infrastructure (U-NII) band with orthogonal frequency division        multiplexing (OFDM) to deliver up to 54 Mb/s data rates;    -   IEEE 802.11b-1999 designed for the 2.4 GHz ISM band and uses        direct sequence spread spectrum (DSSS) to deliver up to 11 Mb/s        data rates with reduced range;    -   IEEE 802.11g-2003 designed for the 2.4 GHz ISM band with OFDM at        datarates up to 54 Mb/s;    -   IEEE 802.11k exposes various measurements to facilitate the        management and maintenance of a mobile Wireless LAN;    -   IEEE Std 802.11-2007 Wireless LAN Medium Access Control (MAC)        and Physical Layer (PHY) Specifications;    -   IEEE 802.11n which adds multiple-input multiple output (MIMO)        antennas, channel bonding etc to support data rates to several        100 s Mb/s;    -   IEEE 802.11r which provide continuous connectivity for wireless        devices in motion through fast secure handoffs;    -   IEEE 802.11s which addresses mesh networks;    -   IEEE 802.11u that addresses interoperability of IEEE 802.11        devices with external networks; and    -   IEEE 802.11v that addresses management of STAs.

The IEEE 802.11 Wireless LAN Standard defines at least two differentphysical (PHY) specifications and one common medium access control (MAC)specification. Other wireless LAN standards include: IEEE 802.16a(WiMAX), UMTS (Universal Mobile Telecommunication System), EV-DO(Evolution-Data Optimized), CDMA 2000, GPRS (General Packet RadioService), EDGE (Enhanced Data Rates for GSM Evolution), Open Air (whichwas the first wireless LAN standard), HomeRF (designed specifically forthe home networking market), and HiperLAN1/HiperLAN2 (the Europeancounterpart to the “American” 802.11a standard). Bluetooth is a personalarea network (PAN) standard alongside other standards such as ZigBee(including IEEE 802.15), Wireless USB, 6IoWPAN (IPv6 over Low PowerWireless), and UWB (ultra-wideband). PAN standards typically addressinglow-power, short-range, wireless connections.

For the purposes of defining aspects of wireless networks and theiroperating principles the background and embodiments of the inventionwill be described with respect to the IEEE 802.11 Wireless LAN Standard,which describes two major components, the mobile station (STA) and thefixed access point (AP). It would be understood by one skilled in theart that the embodiments of the invention and the principles within thespecification overall may be applied to other wireless networks,including but not limited to those operating to standards such as thosedefined supra.

IEEE 802.11 networks can also have an independent configuration wherethe mobile stations communicate directly with one another, withoutsupport from a fixed AP. The medium access control (MAC) protocolregulates access to the RF physical link in such independentconfigurations and provides basic access mechanisms with clear channelassessment, channel synchronization, and collision avoidance using theCarrier Sense Multiple Access with Collision Avoidance (CSMA/CA) accessmethod. The MAC also provides link setup, data fragmentation,authentication, synchronization, encryption, and power management.

Synchronization is the process of STAs in an IEEE 802.11 wireless LANcell getting in step with each other, so that reliable communication ispossible. The MAC also provides the basis for synchronization mechanismsthat allow for some physical layers to make use of frequency hopping orother time-based mechanisms wherein the parameters of the physical layerchange with time. This process involves an AP sending a beacon frame toannounce the presence of a wireless LAN cell or a STA inquiring to finda wireless LAN cell. Once a wireless LAN cell is found, a STA joins thewireless LAN cell in a process managed by the distributed wireless LANcells.

In an independent BSS (IBSS) wireless LAN cell, there is no access point(AP) to act as the central time source for the wireless LAN cell. Insuch an IBSS a wireless LAN cell timer synchronization is distributedamong the mobile STAs of the IBSS wireless LAN cell. Since there is noAP, the mobile STA that starts the IBSS wireless LAN cell will begin byresetting its TSF timer to zero and transmitting a beacon frame. Thisestablishes the basic beaconing process for this IBSS wireless LAN cellafter which each STA will attempt to send a beacon after the targetbeacon transmission time (TBTT) arrives. To minimize actual collisionsof the transmitted beacon frames on the medium, each STA in the wirelessLAN cell will choose a random delay value, which it will allow to expirebefore it attempts its beacon transmission.

In order for a STA to communicate with other STAs in a wireless LANcell, it must first find the AP. The process of finding another STA isby inquiry, which may be either passive or active. Passive inquiryinvolves only listening for IEEE 802.11 traffic whereas active inquiryrequires the inquiring STA to transmit and invoke responses from IEEE802.11 APs and allows an IEEE 802.11 STA to find a wireless LAN cellwhile minimizing the time spent inquiring. Once all responses arereceived, or the STA has decided there will be no responses, it maychange to another channel and repeat the process. At the conclusion ofthis the STA has accumulated information about the wireless LAN cells inits vicinity. To join the selected wireless LAN cell all of the STA'sMAC and physical parameters must be synchronized with the desiredwireless LAN cell. Once this is complete, the STA has joined thewireless LAN cell and is ready to begin communicating.

Each STA and AP in an IEEE 802.11 wireless LAN implements the MAC layerservice, which provides the capability for STAs to exchange MAC frames.The MAC layer transmits management, control, or data frames between STAsand APs, which once formed is passed to the Physical Layer fortransmission. But before transmitting a frame, the MAC layer must firstgain access to the network. Three interframe space (IFS) intervals deferan IEEE 802.11 STA's access to the medium and thus provide one mechanismof establishing priority, but for the STA and not its traffic. Each IFSdefines the duration between the end of the last symbol of the previousframe to the beginning of the first symbol of the next frame. The ShortInterframe Space (SIFS) provides the highest priority level by allowingsome frames to access the medium before others.

The Priority Interframe Space (PIFS) is used for high priority access tothe medium during the contention-free period. A point coordinator in theAP connected to the backbone network controls the priority-based PointCoordination Function (PCF) to dictate which STAs in a cell can gainaccess to the medium by sending a contention-free poll frame to a STA,thereby granting the STA permission to transmit a single frame to anydestination.

The Distributed Coordination Function (DCF) Interframe Space (DIFS) isused for transmitting low priority data frames during thecontention-based period. The DIFS spacing delays the transmission oflower priority frames to occur later than the priority-basedtransmission frames.

During the contention-based period, the DCF uses the Carrier-SenseMultiple Access with Collision Avoidance (CSMA/CA) contention-basedprotocol, which is similar to IEEE 802.3 Ethernet. This CSMA/CA protocolminimizes the chance of collisions between STAs sharing the medium byutilizing a random back-off interval to delay transmission by a STA.

Within the IEEE 802.11 Standard, the channel is shared by a centralizedaccess protocol, the Point Coordination Function (PCF), to providecontention-free transfer based on a polling scheme controlled by the APof a BSS. This feature, however, is typically not exploited incommercial systems. The centralized access protocol gains control of thechannel and maintains control for the entire contention-free period bywaiting the shorter Priority Interframe Space (PIFS) interval betweentransmissions than the STAs using the Distributed Coordination Function(DCF) access procedure. Following the end of the contention-free period,the DCF access procedure begins, with each STA contending for accessusing the CSMA/CA method. The 802.11 MAC Layer thereby provides bothcontention and contention-free access to the shared wireless mediumthrough the use of various MAC frame types to implement the requiredfunctions of MAC management, control, and data transmission.

Quality of service (QoS) is a measure of service quality provided to acustomer, using the STA. The primary measures of QoS are message loss,message delay, message jitter, and network availability. Voice and videoapplications have the most rigorous QoS requirements. Interactive dataapplications such as Web browsing have lower delay and lossrequirements, but they are sensitive to errors. Non-Real Timeapplications such as file transfer, email, and data backup operateacceptably across a wide range of loss rates and delay. Prioritizedpacket scheduling, packet dropping, and bandwidth allocation are amongtechniques available, within the prior art, at the various nodes of thenetwork, including APs, that enable packets from different applicationsto be treated differently, thereby helping to achieve different QoSobjectives. Many network providers guarantee specific QoS and capacitylevels through the use of Service-Level Agreements (SLAs). An SLA is acontract between an enterprise user and a network provider thatspecifies the capacity (and possibly other performance measures) to beprovided between points in the network that must be delivered with aspecified QoS. If the network provider fails to meet the terms of theSLA, then the user may be entitled to some form of compensation. The SLAis typically offered by network providers for private line, frame relay,ATM, or Internet networks employed by enterprises and generally only forwired services due to issues including, but not limited to, access,contention, data rates that have been discussed above as well as otherssuch as handover between APs during roaming, for example, that arediscussed below.

The problem of overlapping AP coverage is acute when wireless LANs areinstalled without any awareness of what other wireless LANs areoperating nearby. Consequently, multiple-cell wireless LANs typicallyrely on a medium access control (MAC) protocol to allocate channel timeamong STAs in order to avoid co-channel interference between APs, justas it avoids contention among STAs within the same cell associated withan AP.

Additional MAC protocols are provided for wireless LANs becausetransmission may be flawed by higher bit error rates and differentlosses that are experienced on a wireless channel depending on the pathon which the signal travels. Additive noise, path loss and multipathinterference result in more retransmissions and necessitate additionalacknowledgements, as successful transmission cannot be taken forgranted, all of which further reduce the actual bandwidth available tothe traffic the STA is trying to send or receive. These effects, amongstothers such as physical barriers, can also result in what are known as“hidden” STAs wherein an STA is visible to an AP but not from other STAscommunicating with the AP. Accordingly, these STAs that cannot hear orbe heard by a source STA are capable of causing interference to thedestination STA of a transmission. Generally, a message exchangemechanism known in the art as Request-to-Send/Clear-to-Send (RTS/CTS)alleviates the hidden terminal problem. RTS/CTS may also provide areservation mechanism that can save bandwidth in wireless LANs. Theinability to detect a collision as quickly as it can be detected oncable with carrier-sense multiple access with collision detection(CSMA/CD) causes more channel time to be wasted in a collision whilewaiting for the entire frame to transmit before the collision isdetected. Hence, carrier sensing is combined with the RTS/CTS mechanismto give carrier-sense multiple access with collision avoidance(CSMA/CA).

To address enhancements to the MAC protocols for achieving acceptableQoS for WLANs IEEE 802.11e-2005 (IEEE 802.11e) was formalized as anapproved amendment to the IEEE 802.11 standard by providingmodifications to the MAC. The standard is considered of criticalimportance for delay-sensitive applications, such as Voice over WirelessLAN and streaming multimedia, and has subsequently been incorporatedinto the IEEE 802.11-2007 standard. IEEE 801.11e provides for enhancedDCF (EDCF) and enhanced PCF (EPCF) through a new coordination function,the hybrid coordination function (HCF). IEEE 801.11e also includesadditional Admission Control in that the AP publishes availablebandwidth in beacons such that STAs can check the available bandwidthbefore adding more traffic.

The EDCF mechanism employs the Tiered Contention Multiple Access (TCMA)protocol that has basic access rules that similar to CSMA but nowtransmission deferral and backoff countdown depend on the priorityclassification of the data. A STA still waits for an idle time intervalbefore attempting transmission following a busy period, but the lengthof this interval is no longer equal to DIFS but equal to theArbitration-Time Inter-Frame Space (AIFS), which varies with thepriority of the data. Equally, for high priority data contention window(CW) duration is reduced such that the random back-offs are shorter.Additionally, IEEE 802.11e provides contention-free access to thechannel for a period called a Transmit Opportunity (TXOP), which is abounded time interval during which a STA can send as many frames aspossible. Accordingly, higher priority data gets to the channel faster.Additionally, countdown of the backoff timer in an STA does not commencewhen a busy period completes unless the channel has been idle for aperiod. This causes the backoff countdown of lower priority data framesto slow down and even freeze if there are higher-priority frames readyto transmit. This slow down/freezing is a common occurrence insituations of congestion thereby limiting transmission of data framesthat have a priority below that of those seizing and holding thechannel. The Wi-Fi Alliance (a trade association that promotes wirelessLAN technology) certifies products if they conform to interoperabilitystandards, such as Wireless Multimedia Extensions (WME) (also known asWi-Fi Multimedia (WMM)) which is based on the IEEE 802.11e standard. WMMcertified APs must be enabled for EDCA and TXOP whilst all other IEEE802.11e enhancements are optional.

The EPCF maintains multiple traffic queues at the STAs for differenttraffic categories with higher-priority frames being scheduled fortransmission first. Delays are reduced through improved polling-listmanagement, which maintains only active STAs on it. A STA with data totransmit must reserve a spot on that list, where it stays as long as itis active and for a limited number of inactive polling cycles. As suchIEEE 802.11e provides a generalization of PCF in that it allows forcontention-free transfers to occur as needed; not necessarily atpre-determined regular repeat times. An AP can thus send (and possiblyreceive) data to STAs in its BSS on a contention-free basis. Thiscontention-free session, referred to as a contention-free burst (CFB),helps an AP transmit its traffic, which is typically heavier ininfrastructure cells (since STAs must communicate exclusively throughthe AP).

Attention must also been given to the problem of co-channel overlappingBSSs (OBSSs), particularly with dense deployments. Channel re-use inmultiple-cell Wireless LANs, which is necessary due to the small numberof channels in the unlicensed band, three non over lapping channels forIEEE 802.11b/g (24 for IEEE 802.11a), can lead to a high degree ofoverlap in the coverage areas of co-channel WLAN cells. This overlap isexacerbated by the typically ad hoc placement of WLANs. This alsopotentially poses a problem for the PCF and HCF, as contention-freesessions (CFSs) are generated without coordination among co-channel APswhen contention free periods are enabled. The existing standards do notprovide adequate coordination for contention-free sessions in suchsituations.

Within OBSSs channel access time (or bandwidth) should also be allocatedamong the multiple co-channel cells in order to avoid interference. Tobe efficient, a channel should not remain idle if there is data waitingfor transmission and as channel selection within the IEEE 802.11standard is fixed or static, then bandwidth allocation should be dynamicso that an STA only gets the bandwidth it needs, thereby increasingefficiency. Potentially, this bandwidth allocation may change on aper-transmission basis if something occurs to impact the path, forexample distance from AP increasing or barrier interference.Beneficially, dynamic bandwidth allocation promotes fair access to thechannel for all co-channel cells. The success rate of a STA in accessingits assigned channel either by its AP generating CFSs or by (E)DCFtransmissions, should be independent of its location, assumingcomparable traffic loads. Without a mechanism to manage access underhigh traffic loads transmissions can be delayed excessively in thedisadvantaged cell(s), such that important STAs/sessions do not get thebandwidth they require such that they fail to meet QoS requirements.

Not surprisingly, within the prior art there are multiple disclosures oftechniques and methods for controlling access to Wi-Fi networks as wellas providing QoS, managing congestion, taking APs offline etc that seekto either address the limitations within the IEEE 802.11 standards orextend upon them. A subset of these prior art approaches are discussedbelow in respect of FIGS. 1 through 7. Amongst these techniques are:

Management of Beacon Power, wherein an AP uses beacon frames for exampleto announce the presence of a wireless LAN cell, transmit timinginformation and the length of the contention-free interval. Adjustmentsto the beacon power form the basis of solutions taught in US PatentApplication 2008-0,112,326 “Load Balancing Routes in Multi-Hop Ad-HocWireless Networks”, U.S. Pat. No. 7,715,353 “Wireless LAN CellBreathing”, US Patent Application 2007-0,248,033 “Methods and Devicesfor Balancing the Load of Access Points in Wireless Local AreaNetworks”, and US Patent Application 2007-0,248,059 “Wireless LAN CellBreathing.”

Management of Beacon Timing, see for example U.S. Pat. No. 7,222,175“Dynamically Configurable Beacon Intervals for Wireless LAN AccessPoints.”

Received Signal Strength Indicator (RSSI) and QoS Indicators at STA, seefor example U.S. Pat. No. 7,065,063 “System and Method for BalancingCommunication Traffic Between Adjacent Base Stations in a MobileCommunications Network”, US Patent Application 2009-0,310,569 “Systemand Method for Balancing Communication Traffic Between Adjacent BaseStations in a Mobile Communications Network”, U.S. Pat. No. 7,200,395“Wireless Station Protocol Apparatus”, U.S. Pat. No. 7,158,787 “WirelessStation Protocol Method”, U.S. Pat. No. 7,206,297 “Method forAssociating Access Points with Station using Bid Techniques”, U.S. Pat.No. 7,248,574 “Apparatus for Selecting an Optimum Access Point in aWireless Network”, U.S. Pat. No. 7,274,930 “Distance DeterminationProgram for use by Devices in a Wireless Network”, U.S. Pat. No.7,307,976 “Program for Selecting an Optimum Access Point in a WirelessNetwork on a Common Channel”, and US Patent Application 2004-0,166,867“Program for Ascertaining a Dynamic Attribute of a System.”

AP Loading Determination, see for example US Patent Application2008-0,316,985 “WLAN having Load Balancing Based on Access PointLoading”, U.S. Pat. No. 7,400,901 “WLAN having Load Balancing Based onAccess Point Loading”, U.S. Pat. No. 7,366,103 “Seamless Roaming Optionsin an IEEE 802.11 Compliant Network”, U.S. Pat. No. 7,362,776 “Methodfor Multicast Load Balancing in Wireless LANs”, US Patent Application2004-0,120,290 “Admission Control in a Wireless Communication Network”,and US Patent Application 2008-0,151,807 “Method for Multicast LoadBalancing in Wireless LANs.”

QoS Signaling, see for example US Patent Application 2008-0,101,231“Wi-Fi Quality of Service Signaling.”

Managing STA Attributes and Configuration, see US Patent Application2006-0,165,031 “Apparatus and Method for Delivery handling Broadcast andMulticast Traffic as Unicast Traffic in a Wireless Network”, U.S. Pat.No. 7,146,166 “Transmission Channel Selection Program”, U.S. Pat. No.7,307,972 “Apparatus for Selecting an Optimum Access Point in a WirelessNetwork on a Common Channel”, U.S. Pat. No. 7,369,858 “Apparatus forSelf-Adjusting Power at a Wireless Station to Reduce Inter-ChannelInterference”, US Patent 2004-0,192,279 “Program for Scanning RadioFrequency Channels” “WLAN having Load Balancing Based on Access PointLoading”, and US Patent Application 2008-0,151,807 “Method for MulticastLoad Balancing in Wireless LANs.”

Global Release, predominantly for reacquisition although also forremoving an AP temporarily or permanently. See for example U.S. Pat. No.7,280,517 “Wireless LANs and Neighborhood Capture”, US PatentApplication 2003-0,086,437 “Overcoming Neighborhood Capture in WirelessLANs”, US Patent Application 2008-0,019,343 “Wireless LANs andNeighborhood Capture”, and U.S. Pat. No. 7,647,046 “MaintainingUninterrupted Service in a Wireless Access Point and Client StationsThereof.”

AP Directed Transfer to another AP, see for example US PatentApplication 2006-0058056 “Method for Controlling Handoff betweenSecondary Agents in a Wireless Communications System”, U.S. Pat. No.7,706,326 “Wireless Communications Methods and Components that ImplementHandoff in Wireless Local Area Network”, and US Patent Application2004-0,264,394 “Method and Apparatus for Multi-Channel Wireless LANArchitecture.”

Higher Level Protocols wherein APs are directed, see for example USPatent Application 2007-0,286,202 “Methods and Systems for CallAdmission Control and Providing Quality of Service in Broadband WirelessAccess Packet-Based Networks”, U.S. Pat. No. 7,826,426 “SeamlessMobility in Wireless Networks”, and US Patent Application 2004-0,202,130“Apparatus for Associating Access Points with Stations in a WirelessNetwork.”

AP Characteristics and Configuration, see for example U.S. Pat. No.7,274,945 “Transmission Channel Selection Apparatus”, U.S. Pat. No.7,366,537 “Wireless Network Apparatus and System”, US 2004-0,166,870“Distributed Protocol for use in a Wireless Network”, and US PatentApplication 2004-0,203,688 “Apparatus for Adjusting Channel Interferencebetween Access Points in a Wireless Network.”

Polling STAs, see for example 2008-0,013,522 “Wireless LANs andNeighborhood Capture”, and US Patent Application 2006-0,072,488“Point-Controlled Contention Arbitration in Multiple Access WirelessLANs”, US Patent Application 2005-01,070,263 “Wireless Access PointProtocol Logic”, and US Patent Application 2004-0,202,122 “WirelessAccess Point Protocol Program”

Overall the 802.11 protocol is designed to provide equal opportunity forall STAs to seize the RF channel. However, with differentclasses-of-service, a STA transmitting Real Time traffic should receivepriority in seizing the RF channel to improve delay, jitter and loss tothese services over other traffic either from the same STA or from otherSTAs. Whilst the IEEE standard 802.11e provides a mechanism to achievethis prioritization it requires that both the APs and the STAs supportthis protocol. Critically IEEE 802.11e requires that key elements beapplied to the STAs, which as discussed supra are in the majority ofcases consumer devices that only provides basic IEEE 802.11functionality without QoS or other features. Advanced features such asQoS (IEEE 802.11e) and Signaling for Load Distribution are not expectedto be ubiquitously deployed and available anytime soon for severalfactors including, but not limited to

1. some of these standards are yet not ratified and hence thestandardized functions are not available in Wi-Fi chip sets;

2. modification to applications running on STAs would be required tointerwork with the QoS and traffic management functions that aredeployed in the chip sets; and

3. many legacy STAs will continue to operate even when standards aredeployed so a QoS solution is still needed for these legacy STAs.

Consequently, ubiquitous penetration of such QoS compliant STAs to themore general consumer base in markets for many years. In 2009 the top 5manufacturers sold 888 million devices from a total sales base of 1billion units. Even at these high rates, which are driven by the currentmassive subscriber increases in China and India, and hence likely todrop as market penetration reaches 100% of the world's population, itwould take nearly 6 years to replace all existing handsets in theconsumer's hands with QoS compliant STAs.

Recently, significant attention has been focused on smartphones asopposed to feature phones, together with their operating systems such asAndroid (Google), Apple iOS and Symbian. Smartphones typically allow theuser to install and run more advanced applications as they run acomplete operating system whereas feature phones have less advancedprogramming and are typically based on Java ME or BREW. Yet in both Q3and Q4 2010 (July-September) when compared to 2009 sales were stilldominated by feature phones and in fact low cost feature phonesincreased market share. Overall smartphones currently account for only20% of handset shipments, and typically most consumers today exploitonly voice and data services like the majority of consumers with theirfeature phones.

Equally today, in 2011, Wi-Fi enabled devices typically sold often donot support IEEE 802.11e. Those that do however, such as laptopcomputers and netbooks, generally do not use it due to the nature of theapplications they run. Accordingly, it would be beneficial to provide amethod today that provides for enhancing QoS, provides resilientconnectivity, and increases useable network capacity and bandwidth tousers of Wi-Fi networks when using Real Time services such as voice(VoIP), video and interactive data, as well data services such as email,FTP, web browsing, etc on basic Wi-Fi devices that do not support QoSfeatures.

Providing resilient connectivity between each STA and AP means that eachSTA sees a good RF signal with good Signal to Noise and InterferenceRatio (SNIR). Increasing useable network capacity and bandwidth meansthat each STA can transmit and receive packets using maximumover-the-air data rate and that over-the-air congestion is controlledand minimized. Enhancing service quality means ensuring that delay, lossand jitter are managed to a level where Real Time services perform, forexample voice quality obtains a Mean Opinion Score (MOS) of 3.8 orhigher (where MOS tests for voice are established by ITU-Trecommendation P.800).

Whilst standards are evolving to address some of these issues, however,standards development, ratification and industry adoption are movingslowly. In other areas devices supporting QoS today, such as netbooksand laptops, are either not mass consumer market products or are notsupported by the application. It would thereby be beneficial to providea network-based solution sooner that supports legacy STAs as well as newQoS compliant STAs and additionally augments standards basedQoS-compliant APs.

SUMMARY OF THE INVENTION

It is an object of the present invention to obviate or mitigate at leastone disadvantage of the prior art and introduce new concepts.

In accordance with an embodiment of the invention there is provided amethod comprising:

-   (a) providing an access point supporting at least a communication    session of a plurality of communication sessions, each communication    session associated with a client station of a plurality of client    stations operating according to a first predetermined standard and    comprising a plurality of frames, the access point comprising a    first receiver operating according to a second predetermined    standard, a first transmitter operating according to a third    predetermined standard, an over-the-air measurement block, a load    distribution control block, and a processor;-   (b) determining with the over-the-air measurement block for each    communication session at least one load utilization of a plurality    of load utilizations, each load utilization associated with at least    a predetermined traffic class of a plurality of traffic classes;-   (c) determining with the processor for each traffic class an    accumulated load utilization in dependence upon at least the    plurality of load utilizations relating to the plurality of    communication sessions associated with that traffic class;-   (d) determining with the processor whether a predetermined threshold    of a plurality of thresholds has been exceeded, the predetermined    threshold relating to a predetermined traffic class or a plurality    of traffic classes; and-   (e) triggering an action of a plurality of actions by the load    distribution control block when the determination is that a    predetermined threshold of the plurality of thresholds has been    exceeded.

In accordance with another embodiment of the invention there is provideda device comprising:

-   a first receiver operating according to a first predetermined    standard capable of supporting at least a communication session of a    plurality of communication sessions, each communication session    associated with a client station of a plurality of client stations    operating according to a first predetermined standard and comprising    a plurality of frames;-   a first transmitter operating according to a second predetermined    standard;-   an over-the-air measurement block;-   a load distribution control block;-   a non-transitory tangible computer readable medium encoding a    computer process; and-   a processor for executing the computer process, the computer process    comprising:    -   (a) determining with the over-the-air measurement block for each        communication session at least one load utilization of a        plurality of load utilizations, each load utilization associated        with at least a predetermined traffic class of a plurality of        traffic classes;    -   (b) determining with the processor for each traffic class an        accumulated load utilization in dependence upon at least the        plurality of load utilizations relating to the plurality of        communication sessions associated with that traffic class;    -   (c) determining with the processor whether a predetermined        threshold of a plurality of thresholds has been exceeded, the        predetermined threshold relating to a predetermined traffic        class; and    -   (d) triggering an action of a plurality of actions by the load        distribution control block when the determination is that a        predetermined threshold of the plurality of thresholds has been        exceeded.

In accordance with another embodiment of the invention there is provideda non-transitory tangible computer readable medium encoding a computerprocess for execution by a processor, the computer process comprising:

-   (a) determining with the over-the-air measurement block for each    communication session at least one load utilization of a plurality    of load utilizations, each load utilization associated with at least    a predetermined traffic class of a plurality of traffic classes;-   (b) determining with the processor for each traffic class an    accumulated load utilization in dependence upon at least the    plurality of load utilizations relating to the plurality of    communication sessions associated with that traffic class;-   (c) determining with the processor whether a predetermined threshold    of a plurality of thresholds has been exceeded, the predetermined    threshold relating to a predetermined traffic class; and-   (d) triggering an action of a plurality of actions by the load    distribution control block when the determination is that a    predetermined threshold of the plurality of thresholds has been    exceeded.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the attached Figures, wherein:

FIG. 1 depicts a schematic of load balancing according to the prior artof U.S. Pat. No. 7,065,063;

FIG. 2 depicts a schematic of managing a WLAN according to the prior artof U.S. Pat. No. 7,280,517;

FIG. 3 depicts a schematic of managing handoff according to the priorart of U.S. Pat. No. 7,706,326;

FIG. 4 depicts a schematic of load balancing according to the prior artof US Patent Application 2008-0,151,807;

FIG. 5 depicts a schematic of beacon power management according to theprior art of U.S. Pat. No. 7,715,353

FIGS. 6 and 7 depicts a schematic of global release according to theprior art of U.S. Pat. No. 7,647,046;

FIG. 8 depicts a schematic of managing mobility with a higher levelcontroller according to the prior art of U.S. Pat. No. 7,826,426;

FIG. 9 depicts a representative WLAN architecture;

FIG. 10 depicts the RF physical architecture of a representative STA;

FIG. 11 depicts the protocol architecture of a representative STA;

FIG. 12 depicts schematically client stations operating over-the-airthat do not support IEEE 802.11e or WMM features;

FIG. 13 depicts a graph depicting how over-the-air delay varies withover-the-air utilization;

FIG. 14 depicts an AP for managing upstream/downstream according to anembodiment of the invention;

FIG. 15 depicts an allocation between classes according to an embodimentof the invention;

FIG. 16 depicts the benefit of early load distribution as provided byembodiments of the invention;

FIG. 17 depicts multiple thresholding for triggering actions by an AP toimprove over-the-air capacity and reduce discarded frames for QoSperformance according to an embodiment of the invention;

FIG. 18 depicts a scenario for managing AP loading according to anembodiment of the invention;

FIG. 19 depicts a flow chart depicting actions for an AP according to anembodiment of the invention where over-the-air utilization exceeds apredetermined threshold;

FIG. 20 depicts a deployment scenario and the resulting interferencearising therefrom as addressed by an embodiment of the invention;

FIG. 21 depicts multiple thresholding for triggering actions by an AP toimprove over-the-air capacity and QoS performance according to anembodiment of the invention wherein there are two BSS's per channel;

FIG. 22 depicts an AP for managing upstream/downstream transmissionsaccording to an embodiment of the invention wherein the AP supportsmultiple BSS's;

FIG. 23 depicts multiple thresholding for triggering actions by an AP toimprove over-the-air capacity and QoS performance according to anembodiment of the invention wherein the AP supports multiple BSS's;

FIG. 24 depicts exemplary process flows for adjacent channelinterference mitigation by an AP according to embodiments of theinvention; and

FIG. 25 depicts exemplary process flows for adjacent channelinterference mitigation by a STA according to embodiments of theinvention.

DETAILED DESCRIPTION

The present invention is directed to wireless networks and morespecifically to managing access and ensuring quality of service withinwireless networks.

For the purposes of defining aspects of wireless networks and theiroperating principles the background and embodiments of the inventionwill be described with respect to the IEEE 802.11 Wireless LAN Standard,which describes two major components, the mobile station (STA) and thefixed access point (AP). It would be understood by one skilled in theart that the embodiments of the invention and the principles within thespecification overall may be applied to other wireless networks,including those operating to standards such as those defined supra.

Within the following description of embodiments of the invention“Service Class” is used to represent a set of traffic that requiresspecific delay, loss, and jitter characteristics from the network (see“Configuration Guidelines for DiffServ Service Classes” InternetEngineering Task Force, RFC 4594, August 2006). Conceptually, a serviceclass pertains to applications with similar characteristics andperformance requirements. Two service classes are addressed in theembodiments, Real Time Class and Data Class. The Real Time Classincludes voice and video that have strict requirements in terms ofdelay, loss and jitter and is composed dominantly of UDP traffic. TheData Class includes all other traffic that is not serviced by the RealTime Class such as Internet surfing, email, FTP, etc., and can generallytolerate larger delay, loss and jitter and is composed dominantly of TCPtraffic. It would be evident that the embodiments of the invention arenot limited to just two classes of traffic and that multiple classes maybe provided without departing from the scope of the invention.

Within the following description of embodiments of the invention “ClientStation” is used to describe a STA, a Wi-Fi based device used by theend-user and which associates to an access point (AP). STAs used onlyfor voice communications are often called handsets or Wi-Fi phones.General purpose multi-application wireless hand held devices are oftencalled Smartphones. Other multi-application wireless devices are PDAs,netbooks, laptops, tablets, etc. It would be apparent to one skilled inthe art that embodiments of the invention are applicable to any Wi-Fibased device that accesses a Wi-Fi network.

Within the following description of embodiments of the invention“Over-the-air Bandwidth” is used to describe the raw bandwidth that isavailable on the RF channel (i.e., between the AP and STAs) to carry adigital signal and is usually measured in bits per second.

Within the following description of embodiments of the invention“Over-the-air Utilization” is used to describe a measure of the averageamount of over-the-air bandwidth being used relative to the totalavailable. It is also a measure of the relative amount of time the RFchannel is in use. In both cases it is usually measured as a ratio inpercent.

Reference may be made below to specific elements, numbered in accordancewith the attached figures. The discussion below should be taken to beexemplary in nature, and not as limiting of the scope of the presentinvention. The scope of the present invention is defined in the claims,and should not be considered as limited by the implementation detailsdescribed below, which as one skilled in the art will appreciate, can bemodified by replacing elements with equivalent functional elements.

FIG. 1 depicts a schematic of load balancing according to the prior artof U.S. Pat. No. 7,065,063 entitled “System and Method for BalancingCommunication Traffic Loading between Adjacent Base Stations in a MobileCommunications Network” by P. H. Tran (Tran). First schematic 100Adepicts a block diagram of an exemplary roaming system for a mobilecommunications device 132. The mobile device 132 includes at least aprocessor 134, a communications subsystem 133, an antenna 135, and astorage device 144. The roaming system includes a roaming module 136 anda trafnum store within the storage device 144. The roaming module 136may be for example a software module executing on the processing device134, and includes a roaming control sub-module 138, a trafnum trackingsub-module 140, and an RSSI adjustment sub-module 142. In onealternative embodiment, the roaming module 136 may instead execute on anadditional processing device within the communications subsystem 133,such as a digital signal processor (DSP). Also illustrated is a currentbase station 146 and two adjacent base stations 148 and 149.

The term “trafnum” is commonly used to denote a traffic indicator,originally in the Mobitex network which was the first wireless networkto provide always on, wireless push email services and used by the firstmodel of Research in Motion's BlackBerry and PDAs such as the Palm VII,and indicates the number of wireless devices operating which it intendsto send packets to within the next cycle. Within the context of FIG. 1it is used generically to refer to traffic indicators and relateddevices, such as the trafnum store 144 and trafnum tracking sub-module140. The roaming control sub-module 138 monitors signals received by thecommunications subsystem 133 from both the current base station 146 andone or more adjacent base stations 148, and measures an RSSI value foreach signal. In addition, the roaming control sub-module 138 identifiesa base station traffic indicator from the current base station 146. Thesize of this list of identifiers, commonly referred to as a trafnum, isdependent upon the number of devices that have traffic pending at thebase station, and thus is a reliable indicator of the load on the basestation. A stable traffic indicator for a current base station 146 may,for example, be calculated by averaging the trafnum values for a basestation extracted from multiple control frames, such as SVP6 frames.

The roaming control sub-module 138 is typically able to monitor only thetrafnum value for the current base station 146. Therefore, as the mobilecommunications device 132 roams between base stations 146, 148, thetrafnum tracking sub-module 140 records the trafnum value from thecurrent base station 146 in the trafnum store 144. For instance, if themobile communications device 132 has recently roamed from the adjacentbase station 148, then the last trafnum value detected from that basestation 148 would be recorded by the trafnum tracking sub-module 140 inthe trafnum store 144. In addition, the recorded trafnum values 144 aredecreased or “aged” over time by the trafnum tracking sub-module 140such that a stored trafnum value will be reduced to zero (0) after apredetermined aging time interval. For instance, if the aging timeinterval is 120 minutes, then the trafnum aging function may beperformed by the trafnum tracking sub-module 140 using a linear agingformula, for example, where the particular formula may be adaptedaccording to communication network operator or mobile communicationsdevice owner preferences, for example. An exemplary nonlinear trafnumaging scheme would involve maintaining a trafnum value in the trafnumstore 144 for a predetermined period of time, and then reducing thetrafnum value to zero at the expiry of the predetermined period.

The storage of trafnum values by the trafnum tracking sub-module 140reduces the occurrence of “ping-pong” roaming of mobile communicationdevices 132 between congested base stations. The aging of trafnum valuesalso allows a device to retry congested base stations after permittingtime for the congestion to potentially abate. Consequently, the rate oftrafnum aging affects the rate of “ping-pong” roaming. An aging timeinterval may, for example, be adjusted automatically by the trafnumtracking sub-module 140 or may be responsive to a control input from anetwork operator, a mobile communications service provider, or a mobiledevice user. The RSSI adjustment sub-module 142 receives the appropriateRSSI values and trafnum values from the roaming control sub-module 138,and calculates the RSSI_ADJ values for the current and adjacent basestations 146 and 148. If no trafnum value has been recorded for aparticular base station (because the mobile communications device 132has never roamed there), then the base station is assigned a defaulttrafnum value, such as zero (0). The RSSI adjustment sub-module 142 may,for example, calculate the RSSI_ADJ values using Equation (1):

RSSI_ADJ=RSSI_MAX(0,MIN(12,Offset))  (1)

where Offset=2*(trafnum−3).

The value of the term MAX(0,MIN(12,Offset)) in the above equationrepresents the amount by which the RSSI value is attenuated (in dB)depending upon the traffic load on the base station. The “MIN” componentof the equation term MAX(0,MIN(12,Offset)) sets the maximum attenuationat 12 dB, and provides an “offset” term which in this example providesfor attenuation increments of 2 dB and establishes a trafnum of 3 as athreshold loading at or below which a base station's RSSI will not beattenuated. It should be understood, however, that the values used inthe above equation were selected for illustrative purposes only, and arenot intended as a limitation of the claimed invention. It should also beunderstood that the RSSI adjustment sub-module 142 may calculate theRSSI_ADJ values using other equations. For example, an analogousequation may instead be used for increasing the RSSI of base stationswith relatively low traffic loads. Thus, the roaming module 136 maystore or input both RSSI and RSSI_ADJ values for a current base station146 and a plurality of adjacent base stations, 148 and 149. For eachbase station, these values may be stored or input as triplets includinga base station identifier, an RSSI value, and an RSSI_ADJ value.Accordingly, within one subset of solutions in the prior art, the RSSIand RSSI_ADJ are processed as described above to identify roamcandidates and to determine whether a mobile communications deviceshould roam to one of the roam candidates. Than extends the prior artwherein known roaming modules and algorithms used only RSSI values tomake such determinations.

Referring now to the second schematic 100B there is depicted a flowdiagram of an exemplary roaming method that utilizes an adjusted RSSIvalue according to the prior art of Than. The method starts at step 112.At step 114, the mobile communications device measures the signalstrength of its current base station and one or more adjacent basestations (base stations with overlapping coverage), and calculates asignal strength indicator, such as an RSSI value, for each base station.Methods of measuring the signal strength of a base station andcalculating a signal strength indicator, such as an RSSI value, from thesignal strength measurement are well known in the field of mobilecommunications. In step 116, the signal strength indicator for each basestation is adjusted by an amount dependent upon the current loading ofthe base station. The adjusted signal strength indicator (RSSI_ADJ) iscalculated using the measured signal strength indicator (RSSI) and abase station traffic indicator, such as a trafnum value. Based on thetraffic indicator, the RSSI value of a base station may be adjustedupward or downward, such as described above in respect of Equation (1).At step 118, the RSSI_ADJ value of the current base station is comparedwith the RSSI_ADJ values of one or more adjacent base stations toidentify possible roam candidate base stations. The adjacent basestation with the highest RSSI_ADJ value that is also at least a certainthreshold amount greater than the RSSI_ADJ value of the current basestation is selected as a roam candidate at step 120. If none of theadjacent base stations meet this criterion, however, then no roamcandidate is selected and the method ends at step 126.

If a roam candidate is selected in step 120, then its RSSI is comparedwith a pre-selected minimum threshold RSSI value at step 122. If theRSSI of the roam candidate base station is not greater than this minimumthreshold value, then the method ends (step 126) and the mobilecommunications device remains on its current base station. If the roamcandidate has an RSSI value greater than the minimum threshold, however,then the mobile communications device roams to the roam candidate basestation at step 124. In the teachings of Than the minimum thresholdmeasured in step 122 relates to the measured RSSI values, similar toknown prior art roaming methods. Since the minimum threshold in step 122is associated with physical limitations of a mobile communicationsdevice, below which communication signals cannot be reliably transmittedand/or received, the measured RSSI values are preferably used. However,unlike the prior art roaming methods, the initial selection of apossible roam candidate base station at step 118 is made on the basis ofRSSI_ADJ values. Thus, the method effectively pre-processes or adjustsRSSI values of a current and one or more adjacent base stations, anduses the adjusted values to select roam candidate base stations.

In an alternate embodiment, adjusted values may be used for fewerroaming method operations. For instance, in step 120, a mobilecommunications device may determine whether a possible roam candidatebase station, selected based on its RSSI_ADJ value, has an RSSI valuethat is at least a certain threshold amount greater than the RSSI valueof the current base station. Selection of candidate base stations forroaming is based on RSSI_ADJ values, whereas the final determination asto whether the mobile communications device should roam to an adjacentbase station is dependent upon relative RSSI values. The threshold valueused in step 122 may also be adjusted, based on a trafnum value for aselected roam candidate base station for example, so that RSSI_ADJvalues may be used throughout the roaming method. Because both RSSI andRSSI_ADJ values will typically be readily available however, roamingmethods in which both RSSI and RSSI_ADJ values may provide the mostefficient use of processing and memory resources.

However, it would be evident to one skilled in the art that thedetermination of roaming from one AP to another in the prior art of Thanis simply based upon the determined RSSI for the current active andadjacent APs and overall traffic loading, trafnum, of the respectiveAPs. Accordingly, the STA determines whether to move based solely uponthe RSSI and number of devices to transmit to for each AP. Accordingly,if the adjacent nodes do not offer any better figure of merit the STAwill not disassociate from the current AP, as will all other STAs makingthe same determination for that AP. There is no consideration of thetraffic of the STA, the traffic of other STAs and the delay that the STAis currently experiencing with the AP for the traffic class it istransmitting or receiving. Accordingly, the prior art of Than does notprovide an AP with a means to manage the QoS of STAs associated with it.

Now referring to FIG. 2 there is depicted a schematic 200 for atechnique of managing a WLAN according to the prior art of U.S. Pat. No.7,280,517 entitled “Wireless LANs and Neighborhood Capture” by M.Benviste (Benviste). Within schematic 200 three APs are depicted thathave been assigned the same channel, commonly referred to as aco-channel group, which are referred to as APs A, B, and C and comprisenine STAs. APs are depicted as dotted areas, and STAs are labelednumerically. STAs 1, 2, and 3 make up AP A with STA 3 serving as the APfor AP A. STAs 4, 5, and 6 make up AP B with STA 4 as AP B's AP. STAs 7,8, and 9 make up AP C with STA 9 as the AP for AP C. APs A and C are notwithin interference range of each other, so they are called a re-usegroup. STAs in the pair of APs A-B or B-C are, however, within possibleinterference range of one another. In the A-B AP pair, STA 2 of AP A andSTA 5 of AP B are both in the possible interference range of oneanother. Correspondingly, in the B-C AP pair, STA 6 of AP B and STA 7 ofAP C are both in the possible interference range of one another.

All STAs use a CSMA-type of protocol to access the channel, whichinvolves some form of carrier-sensing (either actual or virtual) andhandle traffic at three priorities, top, medium, and low. A STA willrefrain from transmitting while the channel is busy, and transmissionwill be deferred until the backoff timer expires. Backoff countdownoccurs while the channel is sensed idle and an idle time interval equalto the AEFS for the priority of the pending transmission has elapsedfollowing a busy period. Because different APs hear differenttransmissions, depending on their location relative to other co-channelAPs, their backoff countdown rates are different. As a consequence, AP Bwill have difficulty accessing the channel and in operation a STA in APA may transmit at the same time as a STA in AP C. STAs in AP A mustrefrain from transmitting only when STAs in AP B are transmitting. STAsin AP B are preempted from accessing the channel by transmissions ineither of its interfering neighbors, APs A or C. Because transmissionshave variable lengths, it is very likely under loaded traffic conditionsfor a STA in AP A to start a transmission before a transmission in AP Cexpires, and vice versa. As a result, APs A and C will capture thechannel, not allowing STAs in AP B to transmit. In general, one wouldexpect that periphery APs, for example APs at the top or bottom floorsof a multiple-story building equipped with a multiple-AP WLAN, to belikely to capture the channel, at the expense of APs in the sameco-channel group located in the interior. In this instance, an AP isdisadvantaged not only because it's competition for the channel—namely,the re-use group comprising APs A and C—has a greater combined offeredload, but also because selected STA members of a re-use group maytransmit simultaneously, thus prolonging their retention of the channel.In fact traffic from AP B that may be transmitted would only behigh-priority traffic when APs A and C are not transmitting. All othertraffic from AP B would be blocked by traffic from APs A and C eventhough the traffic from APs A and C was medium- or even low-priority.This phenomenon, being commonly referred to in the prior art asneighborhood capture, has a negative impact on QoS delivery.

Transmissions in APs outside the re-use group capturing the channel willbe delayed excessively as transmissions will find the channel busy forlong time intervals. In consequence, CFPs could not be initiated asscheduled and periodic and time-critical data will be delayed. Theprioritization apparatus put in place for EDCF within IEEE 802.11e WMMwill also be rendered ineffective. Accordingly Benviste addresses thiscapture of the PHY by APs A and C by requiring all STAs to release thechannel at pre-specified times. All competing co-channel APs would thushave an equal chance to seize the channel. Global channel release (GCR)should occur at regularly spaced time intervals that are sufficientlyclose to meet delay and jitter restrictions for time-criticalapplications such as voice or video. This implies slotting of thechannel into superframes and synchronization of all STAs.

As shown in schematic 200 wireless STA 3 transmits a timing packet, suchas the beacon frame packet 200 or probe response frame of the IEEE802.11 standard, carrying a superframe timestamp field. Each STAreceiving the timing frame 200 updates its SF clock if the receivedtimestamp is later than the current value of the clock. The initialsetting of the clock when a STA powers on is 0. All STAs in an IBSS APprepare to transmit a beacon frame at a target beacon transmission time(TBTT). Each STA prepares its beacon frame to contain the superframetimestamp value and selects a random delay when it is to transmit itssuperframe timestamp value. In this manner, the superframe timestampvalue is propagated to overlapped STAs, such as wireless STA 5 in FIG.2. At a later target beacon transmission time (TBTT) wireless STA 5 willrelay a superframe timestamp value that is updated with the passage oftime since its receipt, when it transmits its beacon frame. In thismanner, wireless STAs, such as STA 9, which may be out of range ofwireless STA 3, will receive an updated superframe timestamp value. As aresult, the BPs that follow must be foreshortened in order to ensuretermination of the BP at the designated slotted time. However, GCR doesnot eliminate all inequities. By forcing STAs to end their BPs at thesame time, equal access is offered to all STAs in all APs, as there isno synergy of member APs of the same re-use group in retaining thechannel. If traffic loads are equally distributed across APs and re-usegroups, all STAs have a fair/equal chance at the channel. But if thecombined offered load is greater in one re-use group, as is possible forinstance with group A-C which has more STAs, the success rate of AP Bwould be less. GCR improves the success rate of AP B, however, relativeto what the success rate would have been otherwise. To achieve greaterfairness, traffic loads in all re-use groups must be comparable—hencethe need to balance loads not only across APs, but also across re-usegroups.

Irrespective of this limitation within Benviste, in order to avoid theirBPs straddling the superframe boundary, all STAs in the multiple-AP WLANmust be synchronized. Synchronization may be achieved in several ways.For instance, within an AP, STAs may synchronize with the AP, as is donein the current IEEE 802.11 standards. Neighboring APs may besynchronized via frames sent by STAs in the overlapping coverage area oftwo APs. However, time offsets may arise between different APs asdistant APs [APs that cannot hear each other] power on and synchronizelocally, independently of one another. This would happen for exampleearly in the morning when few STAs are on, when an AP is taken offlinefor maintenance, In the former instance as more STAs power on andsynchronize with their neighbors in the course of the day, asynchronymay arise. Clock adjustment is necessary in order to eliminate timeoffsets. Time offsets between APs may be corrected in a way similar tonode synchronization in an independent BSS. As shown in schematic 200the STAs transmit a special frame, such as the beacon frame 100 or proberesponse frame of IEEE 802.11, carrying a superframe timestamp field.Each STA updates its SF clock if the received timestamp is later. Theinitial setting of the clock when a STA powers on is 0.

Other mechanisms are also possible for synchronization such as forinstance, synchronization between APs through a wired distributionnetwork 210 within the WLAN infrastructure. In this manner,synchronization between APs can be maintained by transmitting thesuperframe timestamp over the wired distribution system 210.Additionally, STAs in each AP can communicate with each other and withSTAs in other APs via their AP, which is in communication with the wireddistribution network 210. For example, if STA 1 in AP A hasdata/communication traffic for STA 7 in AP C, then when STA 1 is polledby AP 3 of AP A, STA 1 indicates that it has data for STA 7 of AP C andthe priority of the data. The AP 3 can then poll STA 1 to send the datato the AP 3. If AP 3 is within wireless communication range of AP 9 inAP C, it can attempt to gain channel access to the wireless medium tocommunicate that data to AP 9. If channel access is granted, then AP 3of AP A forwards STA 1's data frames over the wireless medium to AP 9.Alternately, AP 3 can access the wired distribution network to forwardthe frames to STA 9 of AP C for final distribution to STA 7 of AP C. TheAP can use the IEEE 802.3 protocol to access the wired distributionnetwork 210.

Accordingly Benviste teaches to a method of managing access to the PHYoverall by providing a predetermined period wherein all STAs associatedwith all APs are silent before allowing STAs to contend for access tothe PHY. As such over-the-air utilization drops as time is devoted tothe global silence as well as the transmission of the superframes.Further GCR does not manage the loading of APs, but rather managescontention between APs for the same PHY. Additionally Benviste does notmanage the transmissions from each STA within an AP or determinemovement of STAs based upon the traffic carried by them. As suchBenviste does not proactively associate STAs with other APs based uponthe loading of a particular AP nor the traffic content for that AP butsimply prevents particular APs dominating access to the PHY irrespectiveof their loading and traffic pattern.

Now referring to FIG. 3 there is depicted a schematic 300 of managinghandoff according to the prior art of U.S. Pat. No. 7,706,326 entitled“Wireless Communication Methods and Components that Implement Handoff inWireless Local Area Networks” by P. Mariner et al (Mariner). Withinschematic 300 the target AP requests the STA to handoff to the targetAP. The STA decides whether to handoff or not, and communicates itsdecision to the target AP. In the case where the STA decides to goforward with the handoff, the STA notifies the original AP with which itis communicating of its imminent handoff, reconfigures its channel,BSSID, etc. for the target AP, and sends to the target AP a confirmationmessage indicating that it has completed the re-association. Within theteachings of Mariner the target AP determines that the STA should beredirected to it, and further preferably as taught, the target AP usesthe channel being used by the STA in communicating with the original APto send to the STA a DRRq message requesting that the STA handoff to thetarget AP. The target AP subsequently communicates with the STA on thetarget AP's preferred operating channel. The STA determines if itaccepts the redirection request. It communicates its decision to thetarget AP via a DRRsp message, preferably on the target AP's operatingchannel. In the case where the STA accepts the request to handoff to thetarget AP, the STA sends to the original AP a DRI communicating itsdecision, preferably on the original channel that had been used incommunications with the original AP. The STA then reconfigures itself tothe target AP, and sends to the target AP a DRCf message, confirmingthat it has handed off.

Mariner teaches that it is possible to combine the DRRsp with the DRCf,or treat the DRCf as the DRRsp, where the STA determines to accept theredirection request from the target AP. These alternatives eliminate theneed for the STA to switch between communication parameters multipletimes during handover, but imply that either the original AP or thetarget AP are using the same channel or that, after sending the DRRq,the target AP remains on the original AP channel until it receives theDRCf message. The method by which the AP driving the handoff proceduredetermines which AP is a suitable or desired candidate to be the targetAP can include, for example, the STA reporting a list of candidate APs,inter-AP signaling, and centralized decision-making performed at acentral controller. Four different scenarios are presented by Mariner:

1. An original AP requests a WTRU to handoff to a target AP wherein theWTRU then decides whether to handoff or not, and communicates itsdecision to the original AP;

2. An original AP commands a WTRU to handoff to a target AP wherein theWTRU then reconfigures its channel, BSSID, etc. for the target AP, andsends to the target AP a confirmation message indicating that it hascompleted the re-association;

3. A target AP commands a WTRU to handoff to the target AP wherein theWTRU then notifies the original AP of its imminent handoff, reconfiguresits channel, BSSID, etc. for the target AP, and sends to the target AP aconfirmation message indicating that it has completed there-association; and

4. A target AP requests the WTRU to handoff to the target AP wherein theWTRU decides whether to handoff or not, and communicates its decision tothe target AP.

It would be evident to one of skill in the art that the teachings ofMariner whilst teach to commanded and requested transfer of an STA fromone AP to another that the teachings within Mariner require that the STAand AP are implemented with the firmware variants that handle suchcommanded/requested transfer from the AP in addition to the normalhandoff protocols for roaming. Further, whilst Mariner mentions thedirected transfer arising from congestion at an AP there is nodetermination of when this occurs, whether such directions are directedto specific STAs based on traffic type etc. As presented by Mariner theapproach is not dependent of the traffic nor thresholds of over-the-airutilization.

Referring to FIG. 4 there is depicted a flowchart 400 for a method ofload balancing according to the prior art of US Patent Application2008-0,151,807 entitled “Method for Multicast Load Balancing in WirelessLANs” by R. C. Meier et al (Meier). Flowchart 400 depicts a methodaccording to Meier for an AP using implicit admission control to preventexcessive downlink multicast traffic from disrupting multicast andunicast communications and is based on Internet Group ManagementProtocol snooping of Internet Protocol multicast streams. At step 402,the AP categorizes an Internet protocol multicast stream, identified bya destination multicast address, or optionally by a multicastdestination IP address and a unicast source IP address, using InternetGroup Management Protocol snooping. At step 404, a determination is madewhether the Internet protocol multicast stream is admitted orunadmitted. If the Internet protocol multicast stream is admitted, theAP forwards all frames that belong to the implicitly admitted downlinkmulticast stream to the client at step 406. However, if the Internetprotocol multicast stream is unadmitted, a determination is made whethersufficient bandwidth is available for the stream at step 408.

If there is sufficient bandwidth available for the multicast stream, theAP services the multicast stream at step 410. However, if there isinsufficient bandwidth available for the multicast stream, the AP ratelimits frames that belong to the unadmitted multicast stream to theclient at step 412. Thus, implicit admissions control can be used toprotect admitted or unadmitted low bandwidth multicast streams andadmitted high bandwidth multicast streams from high bandwidth unadmittedmulticast streams when the total offered multicast load is greater thanthe available multicast bandwidth available from the AP. For example, adual-mode IEEE 802.11a/g STA needs to be able to roam seamlessly betweenIEEE 802.11b/g APs and IEEE 802.11a APs. Generally IEEE 802.11b STAs arelow bandwidth clients of the WLAN to which they are connected and IEEE802.11a/g STAs are relatively high bandwidth clients. Accordingly Meierteaches to an IEEE 802.11a/g STA roaming to another AP wherein ifsufficient bandwidth is available the STA is serviced fully, otherwisethe STA receives a reduced bandwidth, commonly referred to as beingthrottled back, such that it can be serviced from the new AP to which itis associating.

Accordingly Meier teaches to a method of throttling back STAs to managethe loading at an AP. In contrast it would be beneficial for the APdetermining that it is going to be unable to receive additional trafficload from STAs to dynamically instruct STAs that are active in sendingtraffic on low bandwidth-efficiency connections to disassociate or causethese STAs to roam to APs with lower channel utilization.

Now referring to FIG. 5 there are depicted first and second schematics500A and 500B according to the prior art of U.S. Pat. No. 7,715,353entitled “Wireless LAN Cell Breathing” by K. Jain et al (Jain).Considering initially first schematic 500A there is shown a blockdiagram of a wireless LAN data throughput maximization system comprisesa throughput maximization component 502A. The throughput maximizationcomponent 502A is comprised of a centralized control component 504A thatobtains client received power 506A via an AP 508A and provides AP powercontrol parameters 510A. Optionally, the centralized control component504A can utilize a client received power model 512 to provideinformation regarding client received power without requiring theinformation from the AP 508A. Jain teaches that the optional clientreceived power model 512 can provide a complex estimation and/or asimpler solution such as a ratio indicating how client received power isproportional to AP transmitted power and the like. Jain teaches that theother instances of the throughput maximization component 502A can employdistributed control components as well that can reside in other parts ofa wireless LAN such as, for example, within an AP and the like, tofurther facilitate control of the AP power. The AP power controlparameters 510A can include, but are not limited to, AP power levels,power ON/OFF commands, and/or power level increase/decrease information(e.g., percentage reduction of power over time e.g., 10% each minute for10 minutes, etc.) and the like.

Now referring to second schematic 500B an illustration of a wireless LANemploying a wireless LAN data throughput maximization system 502B inaccordance with an aspect of an embodiment is depicted. The wireless LANdata throughput maximization system 502B is comprised of a centralizedcontrol component 512B and APs “1-Z” 506B to 510B respectively, where Zis an integer from one to infinity. A first client 504B can interactwirelessly with the APs “1-Z” 506B-510B. The centralized controlcomponent 312B provides AP beacon power control for the APs “1-Z” 506Bto 510B respectively to maximize data throughput and/or optimize powerof the wireless LAN. For example, if AP “2” 508B has heavy clientdemand, the centralized control component 512B can reduce the beaconpower level for AP “2” 508B and/or raise the beacon power for AP “1”506B and/or AP “Z” 510B. The first client 504B typically automaticallyattempts to acquire the stronger signal from AP “1” 506B or AP “Z” 510Bwhen AP “2” 508B is no longer receivable. Therefore, Jain teaches thatby controlling the power levels of the APs “1-Z” 506B to 510Brespectively, the first client 504B can be manipulated into accessingthe wireless LAN 502B at a different AP without any modifications to theclient itself. In another instance, the functions of the centralizedcontrol component 512B can be located in one of the APs “1-Z” 506B to510B respectively or distributed among the APs “1-Z” 506B to 510Brespectively rather than at a central location. In the latter scenariointeraction between the APs “1-Z” 506B to 510B respectively may benecessary to coordinate AP power levels.

Now consider, second client 504C that is also in communication with AP“2” 508B and which likewise detects that the centralized controlcomponent 512B has either reduced the beacon power level for AP “2” 508Bor raised the beacon powers for AP “1” 506B and/or AP “Z” 510B. Secondclient 504C makes the same determination as first client 504C and seeksto associated with another AP, such as AP “1” 506B or AP “Z” 510B.Depending upon the location of first and second clients 504B and 504Crespectively relative to the APs “1-Z” 506B to 510B respectively theymay associate to the same AP or different APs. Likewise other STAs beingserviced by AP “2” 506B will make their own determinations todisassociate or remain associated. For disassociation to occur an STAmust establish that the other AP is at a higher RSSI relative to thecurrent AP. As would be evident to one skilled in the art the teachingof Jain simply reduces the beacon power, which an AP employs whensending beacon frames, which for example announce the presence of awireless LAN cell, transmit timing information, or the length of thecontention-free interval. Accordingly all STAs will react to the beaconpower reduction with an unpredictable re-association of those STAs thatdisassociate based upon their locations relative to the other APs. Assuch Jain may force significant traffic from one AP to another APthereby overloading the other AP. It would also be evident that the STAsare not moved in any manner that is associated with their traffic,merely their effective distance (as established by the received RSSIs)from the APs in the network.

Studies of public-area wireless networks have shown that STA servicedemands are highly dynamic in terms of both time of day and location andthat STA load is often distributed unevenly among wireless APs. STAstend to localize in particular areas of the network for a wide varietyreasons, including but not limited to the availability of favorablenetwork connectivity (away from deadzones for example), proximity topower outlets, classrooms, meeting rooms, and/or geographic constraintsof other services (e.g., at airport gate areas with arriving anddeparting flights). A consequence of such behavior is sporadic clientcongestion at popular locations within the network. At any one time, alarge percentage of mobile clients communicate with a small subset ofthe APs. These client concentrations create an unbalanced load in thenetwork and complicate capacity planning, making it difficult toaccommodate heavy, concentrated load in different parts of the networkwithout significant, and costly, over-engineering. As Jain notes themapping between clients and the APs that service them is a criticaldeterminant of system performance and resource usage. As Jain notes anAP can get seriously overloaded even when several nearby APs are lightlyloaded as the majority of STAs will associate with the APs with theloudest beacons (i.e., the strength of the received beacon signal ishighest among all neighboring APs).

Jain therefore teaches that one way to address this is to modify theclient association algorithm within the STAs to incorporate the AP'sload in addition to the received signal strength indicator (RSSI) of theAP's beacon. A client associates with the AP that is lightly loaded andwhose beacons have a highest RSSI value. However, this requires that theSTAs are now configured to receive the AP load information, therebypreventing legacy STAs from exploiting the modified associationalgorithm. However, the re-association is still uncontrolled in that allSTAs establishing a louder AP beacon in their vicinity will move whichgiven the clustering of STAs within most networks will mean that theother APs will become heavily loaded. Jain further does not address anyconsideration of the traffic to/from STAs/APs within the associationalgorithm.

Now referring to FIGS. 6 and 7 there are depicted first and secondschematics 600 and 700 respectively of a global release techniqueaccording to the prior art of U.S. Pat. No. 7,647,046 entitled“Maintaining Uninterrupted Service in a Wireless Access Point and ClientStations Thereof” by W. Huang et al (Huang). Referring to firstschematic 600 a flowchart according to an embodiment of Huang is shownthat exploits the IEEE 802.11 protocols for wireless roaming, theseprinciples such as RSSI being described above, that induces roaming fromthe AP under certain conditions. As shown in first schematic 600 in oneembodiment, a first AP carries out a power reduction step 601 to inducewireless roaming in one or more STAs associated with the AP. Accordingto Huang the power reduction is carried out in a plurality of stepsrather than in one step so as to not cause any of the associated STAs tosimply and suddenly lose signal. For example, the first AP, in step 603ascertains whether or not a pre-defined minimum power level has beenreached, and if not, then in step 605 the AP waits for a pre-definedtime interval, and repeats the power reduction step 601. In a particularembodiment, the power reduction is carried out in six or seven steps.For example, suppose the first AP is transmitting at 100 mW. The firstreduction (step 603) of communication power is to 75 mW, the second to50 mW, the third to 30 mW, the fourth to 20 mW, the fifth to 10 mW, andthen finally, the sixth instance of step 601 reduces the transmit powerto 5 mW. The pre-defined minimum power level is thus 5 mW. In thisexample, each reduction step is separated in wait step 605 by apre-defined interval of one second.

At the end of the reduction process, there are three possibilities foreach associated, or previously associated, STA. The first possibility isthat the STA has successfully roamed to a different (second) AP. Thesecond possibility is that the STA is still associated with the first APeven when the first AP is transmitting at a minimum power level. Thethird possibility is that there is a catastrophic power drop-off thatcauses the associated STA to be disconnected from the wireless network.Huang teaches that in the case of one or more STAs being associatedstill with the first AP even when that AP is transmitting at thepre-defined minimum power level a management frame to indicate to allassociated STAs that the AP will stop being active at some future pointin time, e.g., that the first AP is going offline at some point in the(near) future. These management frames may be a new management framethat is a broadcast frame broadcast by the AP or it may be amodification of a standard beacon frame.

Continuing with the flowchart in first schematic 600, in step 607, thefirst AP broadcasts a management frame, which in a simple embodiment istransmitted only at the minimum power level used the last instance of603, e.g., 5 mW. In another embodiment of Huang, to ensure that allassociated STAs can successfully roam to another AP, including thoseSTAs that were in a “sleep mode” during the power reduction process, oneor more management frames are also broadcast at a higher power than thepre-defined minimum power level. Such an embodiment that includesrepetition of broadcasting of management frames being depicted in firstschematic 600. In step 609, the first AP ascertains if enough managementframes have been sent, and if the first AP determines not enough, instep 611 the AP waits for a pre-defined time interval and then repeatsstep 607 of broadcasting the management frame. Thus, each step ofbroadcasting the management frame is separated by a preset timeinterval. For example, the preset time interval in one version isselected such that a STA that was asleep during the first broadcastwould be awake after the pre-defined time interval.

Huang also teaches, as shown in second schematic 700, a methodimplemented in a STA wherein as the first AP reduces the power oftransmission then at some stage, shown in step 729, the STA receivessignals from the first AP at a received power level below a pre-definedthreshold, such that the STA, in 727, commences a wireless roamingprocedure to associate itself with a different, say a second AP. In oneembodiment, this second AP is selected from a set of APs stored at theSTA based on beacon frames received from APs. Once the station has instep 727 roamed to another AP, e.g., associated with the second AP, instep 731, communication continues via the new AP. Now consider that asshown in step 721 that the STA is still in communication with the firstAP, as indicated by the signal strength (or measure of received signalquality) above the pre-defined threshold, even after such an AP hasreduced its transmit power to a pre-defined minimum level. In step 723shows the case that the STA wirelessly receives a management frame thatwas broadcast by the AP. Such a management frame, as described above,includes information that announces that the first AP will stop beingactive at a defined time and hence in step 727 the STA initiates theroaming procedure that associates the STA to a second AP from which ithas received a beacon, e.g. that is in it's AP list and therefore withwhich it can communicate. The STA in step 731 then continuescommunication, now via the new AP. The case of no management framereceived is shown as step 725, assuming the AP does not go offline, andthe process cycles back to the start and the AP re-determines whetherthe signal is above or below the threshold. It would be clear to thosein the art that if 729 and 723 are not cases that occur, and the APinstantly goes offline, communication will be (temporarily) lost untilthe client can re-associate with another AP.

Accordingly, it would be evident to one skilled in the art that Huang inteaching the controlled removal of an AP from the network, for examplefor maintenance, teaches to a global release wherein any STAs associatedwith the AP either initiate roaming automatically due to the RSSI oftheir associated AP dropping to below a trigger threshold or that theyreceive a management frame that triggers the roaming process. In eachinstance the STA determines which other AP it will associate with basedupon internally stored data relating to the other APs from which itreceives beacons. An alternate embodiment of the teaching of Huang is toinitiate such a global release as a means of distributing the loading ofSTAs with a network of APs such that, either periodically or upondetermining that congestion is occurring, the power of the AP is reducedthereby triggering roaming in the STAs associated with it. Huang inteaching to reducing the output power in a series of steps teaches tosequentially reducing the received RSSI of the STAs, essentiallyreducing the effective radius of the cell in a series of steps droppingthe STAs that have lowest RSSI first. Hence, as with the other methodsdescribed supra the STAs are dropped based upon their location relativeto the AP they are associated with and the other APs. There is noconsideration of what traffic an STA is handling alone nor the overalltraffic distribution and loading of the AP, and RF signal qualitybetween STA and AP. For example, many STAs at the periphery may be inpower-save mode (not sending or receiving packets) or may be handlingData Class traffic at relatively low bitrate such that reduction of theAP power only removes these STAs without significantly reducing theoverall loading of the AP and over-the-air utilization.

Now referring to FIG. 8 there is depicted a schematic 800 of managingmobility with a higher level controller according to the prior art ofU.S. Pat. No. 7,826,426 entitled “Seamless Mobility in Wireless LANs” byV. Bharghavan (Bharghavan). Schematic 800 depicts a first AP 810 and asecond AP 820 and a set of three wireless devices 830, 840, and 850 anda system coordinator 860. Each of the first and second APs 810 and 820respectively maintains a data structure such as a data structure 870that includes a set of entries, each entry for example including an APidentifier, a value for a state of the AP, a set of identifiers forwireless devices (here shown as BSSIDs), a value that identifies the APcurrently actively communicating with each wireless device, and at leastone value that indicates a received signal strength indicator (RSSI),i.e., a measure of received signal strength, for that communication. Thesystem coordinator 860 handles sharing of information between AP's asneeded to maintain the data structure 870 at each AP.

First AP 810 sends communications to the wireless devices, e.g. firstwireless device 830 whilst the first and second APs 810 and 820 receivecommunications from the first wireless device 830. The systemcoordinator monitors each active wireless communication session andbased on the characteristics of these the system coordinator 860 candetermine which AP will be associated (or reassociated) with thewireless device for active communication. This is represented by thedashed lines in schematic 800 between the system coordinator 860, thefirst AP 810 and the second AP 820. With the teaching of Bharghavan thewireless device does not need to take any action and the handoff,sometimes called a “soft handoff” herein, generally occurs without thewireless device even being aware. Accordingly, no messages are exchangedbetween the wireless device and the AP's to carry out the soft handoff.The infrastructure of the system (i.e., system coordinator and AP's)preferably carries out the soft handoff entirely on its end.

Referring to FIG. 9 there is depicted a representative WLAN architecture900 wherein a remote central exchange 910 communicates with theremainder of the telecommunication service providers network which mayinclude for example a long-haul OC-48/OC-192 backbone or an OC-48 widearea network (WAN). The central exchange 910 is connected to a router920 that interfaces to the AP 930 that provides a Wi-Fi cell 940. Withinthe Wi-Fi cell 940 are a variety of STAs including Wi-Fi phones 950,laptops 960, gaming consoles 970 and 975, smartphones 980, and tablets990. Accordingly these devices present a variety of upstream anddownstream traffic requirements within the Real Time Class and DataClass traffic groups.

Now referring to FIG. 10 there is depicted an exemplary RF physicalarchitecture of a representative device 1000. The device 1000 may, forexample, implement an AP or a STA and includes a physical layerinterface (PHY) 1001 that includes at least one antenna 1002 for thefrequency or frequencies of service (approx. 2.4 GHz and/or approx. 5GHz), a transmit/receive (T/R) switch 1004 for half-duplex operation, atransceiver 1005 that includes a radio frequency (RF) wireless receiver1010, and an RF wireless transmitter 1011. The PHY also includes a modem1007 that includes a demodulator 1012 and a modulator 1013. The receivepath to the demodulator includes an analog-to-digital converter (ADC)1027 to produce samples of the received signal. The device 1000 furtherincludes a medium access controller (MAC processor, or simply MAC) 1014for layer-2 processing of the data link layer (MAC). A computer systemdatabus 1018 may be included in some STAs as may a processor 1015 withassociated memory 1016 that may be directly coupled to the processor1015 or to the MAC 1014 or to both. Within the memory 1016 are storedthe data associated with APs and STAs according to the functionality ofthe device 1000, this data being stored within lookup table 1031.

Referring to FIG. 11 there is depicted the protocol architecture of arepresentative STA as part of a simplified functional diagram of asystem 1100 that includes an STA 1104, an AP 1106, and one or morenetwork devices 1107, such as communication servers, streaming mediaservers, and routers for example. Network devices 1107 may be coupled toAP 1106 via any combination of networks, wired, wireless and/or opticalcommunication links. The STA 1104 includes one or more processors 1110and a memory 1112 coupled to processor(s) 1110. AP 1106 includes one ormore processors 1111 and a memory 1113 coupled to processor(s) 1111. Anon-exhaustive list of examples for any of processors 1110 and 1111includes a central processing unit (CPU), a digital signal processor(DSP), a reduced instruction set computer (RISC), a complex instructionset computer (CISC) and the like. Furthermore, any of processors 1110and 1111 may be part of application specific integrated circuits (ASICs)or may be a part of application specific standard products (ASSPs). Anon-exhaustive list of examples for memories 1112 and 1113 includes anycombination of the following semiconductor devices such as registers,latches, ROM, EEPROM, flash memory devices, non-volatile random accessmemory devices (NVRAM), SDRAM, DRAM, double data rate (DDR) memorydevices, SRAM, universal serial bus (USB) removable memory, and thelike. Alternatively memories 1112 and 1113 may include optical devices(CD ROM, DVD) and magnetic devices, such as a HDD.

STA 1104 may include an audio input element 1114, for example amicrophone, and an audio output element 1116, for example, a speaker,coupled to any of processors 1110. STA 1104 may include a video inputelement 1118, for example, a video camera, and a video output element1120, for example an LCD display, coupled to any of processors 1110. STA1104 includes one or more applications 1122 that are typically stored inmemory 1112 and are executable by any combination of processors 1110.STA 1104 includes a protocol stack 1124 and AP 1106 includes acommunication stack 1125. Within system 1100 protocol stack 1124 isshown as IEEE 802.11 protocol stack but alternatively may exploit otherprotocol stacks such as an Internet Engineering Task Force (IETF)multimedia protocol stack for example. Likewise AP stack 1125 exploits aprotocol stack but is not expanded for clarity. Elements of protocolstack 1124 and AP stack 1125 may be implemented in any combination ofsoftware, firmware and/or hardware. Protocol stack 1124 includes an IEEE802.11-compatible PHY module 1126 that is coupled to one or moreFront-End Tx/Rx & Antenna 1128, an IEEE 802.11-compatible MAC module1130 coupled to an IEEE 802.2-compatible LLC module 1132. Protocol stack1124 includes a network layer IP module 1134, a transport layer UserDatagram Protocol (UDP) module 1136 and a transport layer TransmissionControl Protocol (TCP) module 1138.

Protocol stack 1124 also includes a session layer Real Time TransportProtocol (RTP) module 1140, a Session Announcement Protocol (SAP) module1142, a Session Initiation Protocol (SIP) module 1144 and a Real TimeStreaming Protocol (RTSP) module 1146. Protocol stack 1124 includes apresentation layer media negotiation module 1148, a call control module1150, one or more audio codecs 1152 and one or more video codecs 1154.Applications 1122 may be able to create, maintain and/or terminatecommunication sessions with any of devices 1107 by way of AP 1106.Typically, applications 1122 may activate any of the SAP, SIP, RTSP,media negotiation and call control modules for that purpose. Typically,information may propagate from the SAP, SIP, RTSP, media negotiation andcall control modules to PHY module 1126 through TCP module 1138, IPmodule 1134, LLC module 1132 and MAC module 1130.

It would be apparent to one skilled in the art that elements of the STA1104 may also be implemented within the AP 1106 including but notlimited to one or more elements of the protocol stack 1124, includingfor example an IEEE 802.11-compatible PHY module, an IEEE802.11-compatible MAC module, and an IEEE 802.2-compatible LLC module1132. The AP 1106 may additionally include a network layer IP module, atransport layer User Datagram Protocol (UDP) module and a transportlayer Transmission Control Protocol (TCP) module as well as a sessionlayer Real Time Transport Protocol (RTP) module, a Session AnnouncementProtocol (SAP) module, a Session Initiation Protocol (SIP) module and aReal Time Streaming Protocol (RTSP) module, media negotiation module,and a call control module.

Over-the-Air Bandwidth Demand Overload:

As more STAs associate with an AP and set up sessions (voice, video ordata), the demand from all the devices for access to the over-the-airbandwidth increases resulting in increased delay and loss. Furthermore,STAs with existing associations may start up new sessions with largerbandwidth demand. The result is that demand for over-the-air bandwidthincreases beyond a utilization level where QoS can be met. This is dueto excessive requests from stations and APs for access to the RF channelcausing traffic to be queued in station and AP queues with correspondingdelay. Excessive over-the-air bandwidth demand will also result inincreased collisions and a further reduction in service quality andreduce throughput. The need to distribute this excess traffic over morelightly loaded APs forms a substantial part of the prior art solutionspresented supra, as well as access control mechanisms that have not beenpresented but would be known to one of skill in the art. However, asevident from the discussions supra these prior art solutions addressdifferent capability and require functionality in both the AP and STA.These types of upgrades can be expensive and difficult to implementunder most circumstances but are exacerbated in this instance as theSTAs are consumer devices. A solution is needed that will operate withexisting STAs resulting in lower cost and smoother upgrade to nextgeneration traffic management features. In this manner SLAs can beoffered based upon only upgrades to APs wherein, as will be evident fromthe embodiments described, these upgrades may in some instances beimplemented as firmware/software upgrades.

Wireless Station Priority:

Since wireless STAs are distributed over a large area, they contend forthe over-the-air bandwidth independently of each other. In general, someSTAs, will be transmitting Real Time Class traffic, others Data Classtraffic. The 802.11 protocol is designed to provide equal opportunityfor all STAs to seize the RF channel. However, with classes-of-service,a STA transmitting Real Time traffic should receive priority in seizingthe RF channel to improve delay, jitter and loss to these services toone transmitting Data traffic. The IEEE standard 802.11e provides amechanism to achieve this prioritization; however, as discussed in theBackground, many commercial, currently deployed consumer STAs do notsupport these features and widespread deployment of these features andtheir use may take many years. Accordingly, a network-based solutionaccording to embodiments of the invention which interworks with IEEE802.11e such that only APs need to be retrofitted/installed, and suchretrofits/installations could begin being implemented quickly,complementing IEEE 802.11e functionality. Further, no STA upgrades arerequired beyond today's basic Wi-Fi functionality (IEEE 802.11)according to embodiments of the invention.

General End-User Requirements:

For end-users the goal is for all carried voice and video sessions toreceive near toll quality performance when connected to a Wi-Fi wirelessaccess network. Active Wi-Fi STAs sending and receiving Data Classtraffic will receive good performance as required by the application.

General Solution Requirements:

The new functionality will be added to the network and not the STA aswill be evident from discussion below of exemplary embodiments of theinvention. This will ensure that todays and future smartphones, andother Wi-Fi enabled client devices (laptops, tablets, iPod, netbooks,etc.) will work with this feature set. The solution according toembodiments of the invention does not require new IEEE 802.11 features;i.e. IEEE 802.11e (i.e. RF Priority using Enhanced Distributed ChannelAccess and Traffic Specification (TSpec)), IEEE 802.11k (i.e.Measurements), IEEE 802.11v (i.e. BSS Transition Management) to besupported in the STA or AP. The solution has the following components:Virtual Station Priority; Session Admission Control; Load DistributionControl; and Adjacent Channel Interference Control.

“Virtual Over-the-Air Priority” solutions according to embodiments ofthe invention may coexist with the standards-based “Wireless Multimedia”solution (WMM is based on IEEE 802.11e priority). This means that the APmay properly support clients using the standards-based solution whensupported in the wireless client STA.

Similarly the “Session Admission and Load Distribution Control” solutionmay coexist with a standards-based “Admission Control” solution usingIEEE 802.11e Tspec. It may also coexist with “Load Balance” solutionsusing IEEE 802.11v BSS Transition Management. This means that the AP canproperly support STAs using the standards-based solution when supportedin the STA; otherwise, the AP will apply a solution according to anembodiment of the invention. The AP, typically, will determine whichsolution based upon capability negotiations during STA association withthe AP.

It will be evident to one of skill in the art that the solutions taughtwithin this specification according to embodiments of the invention mayoperate with STAs using IEEE 802.11a,b,g,n standards. Further, thesolutions may operate with STAs using a plurality of BSS also know asESS. Further, these features will operate independently on each VirtualBSS (RF channel partitioned into multiple BSS) and may be configuredseparately.

Virtual Station Priority Overview:

This element of the solution addresses the wireless station priorityissue. A network administrator may assign a maximum level ofover-the-air bandwidth that will be used by each traffic class. Thismanages the demand for the over-the-air bandwidth and hence, manages thequeue delay at a STA and AP. Real Time Class traffic bandwidth ismanaged by forcing STAs to move to another AP when over-the-airbandwidth usage thresholds are reached. Data Class traffic bandwidth ismanaged by using rate control in both directions upstream and downstreamso that over-the-air bandwidth is not saturated. Real Time traffic needsto receive “priority” access to this over-the-air bandwidth over Datatraffic in order to minimize delay. This is accomplished by controllingthe total amount of over-the-air bandwidth used (over-the-airutilization) to assure good QoS, and by allowing Real Time traffic touse all the bandwidth it requires up to a threshold but only allowingthe Data Class to use what is left over (i.e. difference between maximumassigned bandwidth and bandwidth used by Real Time Class.

Session Admission and Load Distribution Overview:

This part of the solution addresses the over-the-air bandwidth overloadissue described supra. Real Time Class traffic sessions are notexplicitly denied on session initialization i.e. a handset associated toan AP starting a voice call will be allowed to proceed. However, whenthe assigned over-the-air bandwidth for Real Time traffic is exceeded,selected session(s) will be handed-off to a near-by AP that has morecapacity to carry the traffic. On reaching or approaching the maximumover-the-air bandwidth usage for Real Time traffic and Data traffic(total utilization for both traffic classes) in the Wi-Fi accessnetwork, new associations may be denied. Some STAs may be disassociatedon severe overload. Accordingly, the network administrator can configurethe Wi-Fi system for:

-   -   usable over-the-air bandwidth for Real Time traffic;    -   usable over-the-air bandwidth for Real Time and Data traffic        (sum total);    -   packet fields which define packets as belonging to the Real Time        Class;    -   over-the-air usage threshold(s) where a new STA association to        the specific AP is discouraged;    -   over-the-air utilization threshold(s) where associated STAs with        active Real Time sessions are encouraged to move to another AP        and    -   over-the-air utilization threshold(s) where associated STAs are        going to be disassociated.

Adjacent Channel Interference Mitigation Overview:

Adjacent channel interference occurs when two wireless STAs are inproximity to each other, each STA is using a different RF channel andeach STA has active (transmitting and receiving packets) sessions. Dueto one or more reasons, including but not limited to mobility, loadbalancing, etc, these STAs are connected to different APs or differentRF channels on the same AP. When one STA is transmitting and the otheris receiving, their close proximity may result in sideband noise beinginjected by the transmitting STA to the receiving STA thereby reducingthe bandwidth (possibly to zero). Adjacent channel interferencemitigation according to embodiments of the invention associates bothdevices with the same AP and channel.

Virtual Station Priority Detailed Description:

As discussed supra a solution is required to ensure that STAs sending orreceiving Real Time Class traffic are given priority on the RF channelover Data Class traffic. This means that STAs sending Real Time trafficwill have lower delay, loss and jitter, and if configured correctly, theSTAs should be able to meet more stringent quality-of-service (QoS)requirements compared to the Data Class traffic.

There is a standards-based solution for traffic prioritization underIEEE 802.11e which requires functionality in both the AP and STA.However, it has only been adopted and implemented in some APs andhigher-priced Wi-Fi STAs. It is not expected to be fully adopted bywidely used end-user (consumer) devices such as smartphones, laptops,netbooks and tablets for several years. Accordingly, most applicationsrunning on such mobile devices will continue to run without using thisQoS feature for some years. This means that QoS capable STAs and non-QoSSTAs will continue to coexist for a long time.

Therefore the inventors have established a network solution, i.e.functionality is implemented only in the AP, and does not require theIEEE 802.11e or WMM QoS feature. Accordingly, embodiments of theinvention work with today's basic Wi-Fi STAs in which applications donot signal their QoS requirements to the network layer. Beneficially, asIEEE 802.11e compliant STAs are deployed in networks alongside legacySTAs both classes of STA can co-exist and interoperate in the same AP.

The basic priority solution within WMM, based upon IEEE 802.11e,operates with four classes of traffic, called Access Categories (AC).These are “Voice”, “Video”, “Best Effort” and “Background” in order ofhighest to lowest priority. Applications running on STAs signal to thenetwork layer requesting a specific priority service. The STA sendinghigher priority packets uses a shorter wait time (i.e. inter framespacing) before attempting to seize the RF channel. Therefore,applications with higher priority traffic wait less time beforeattempting to seize the channel than applications sending low prioritytraffic. All STA packets either go to or come from the AP (i.e.infrastructure configuration). The traffic direction from the STA to theAP is called upstream and traffic direction from the AP to the STA iscalled downstream. The Real Time Class (pertaining to this invention) isintended to include voice and video traffic. This type of trafficusually uses the User Datagram Protocol (UDP) transport protocol andrequires a higher quality-of-service. The Data Class includes allremaining traffic types (i.e. Internet, Data Downloading), withTransmission Control Protocol (TCP) being the dominant transportprotocol.

Traffic Management Procedures:

The purpose of assigning priority to the Real Time traffic type is toensure better QoS for Real Time traffic (voice/video) over traffic inthe Data Class. At present, SLAs for traffic over-the-air interface inWi-Fi wireless systems do not exist. This section describes the trafficmanagement procedures used to achieve virtual priority according toembodiments of the invention. The IEEE 802.11 Distributed ControlFunction, without IEEE 802.11e, allows each STA to have access to theover-the-air bandwidth with approximately equal likelihood. In general,as the over-the-air bandwidth utilization increases so do the delays,loss and jitter for STAs attempting to send packets. This is due to thefact that as the over-the-air channel becomes busier, STAs need to waitlonger to get access to the over-the-air channel leading to longerqueuing delays and possible queue overflows (i.e. loss).

Consider, for example, the scenario shown by FIG. 12 which showsrepresentative STAs (with internal queues) communicating via theover-the-air channel. Application traffic includes such traffic sourcesas Voice-over-IP (VoIP), Video or Hypertext Transfer Protocol (HTTP)packets. As the over-the-air channel load increases through increasedservice demands from already associated STAs and/or through the numberof associated STAs increasing, the over-the-air bandwidth utilizationincreases. Therefore each STA needs to wait a longer period of timebefore they get an opportunity to transmit their data. This delayincrease, as shown by the representative graph in FIG. 12, shows how theover-the-air delay varies with over-the-air utilization (i.e. load).Also shown are representative allocations/partitions of Real Time andData Class allocations and the maximum Data Class allocation accessiblewith no Real Time Class traffic.

In order to maintain good QoS it is desirable to ensure that the totaltraffic load remains below a threshold MaxTU for over-the-airutilization as show in the graph in FIG. 13, this threshold being chosenat a point which provides an acceptable delay. Selecting the threshold‘MaxTU’ also determines how much over-the-air bandwidth will beavailable for Real Time and Data Class traffic, plus an emergencyoverhead between “MaxTU” and 100% utilization. Real Time Class trafficis guaranteed its allocation whilst the Data Class traffic is allowed touse the remaining bandwidth. In order to keep overall traffic levelswithin the threshold, a methodology is required for managing Real TimeClass traffic which is dominated by UDP packets but a different methodis required for managing Data Class traffic which is dominated by TCPpackets.

Referring to FIG. 14 there is depicted an AP 1400 for managing trafficaccording to an embodiment of the invention. Traffic sent from an STA,such as first STA 1490A or second STA 1490B is received at the AP 1400by the Wi-Fi interface (Wi-Fi I/F) 1470. In order to manage each TrafficClass separately, the packets must be classified as belonging to theReal Time Class or Data Class. The packet classifier 1420 decides towhich class the incoming packet belongs, for example based on packetheader fields and other information. After a packet is classified andmetered (bytes and packets counted) it sends byte count informationabout the packet to the Over-the-air Measurement block 1480 to allow itto calculate its over-the-air transmission time. The over-the-airtransmission time is used to calculate the over-the-air utilization forthe Real Time Class and the Total (Real Time and Data Class)over-the-air utilization for all STAs accessing the AP. The Over-the-airMeasurement block 1480 obtains the PHY rate, also needed to calculatethe utilization, from the Wi-Fi I/F block 1470. A detailed explanationof the Over-the-air Measurement Block 1480 and the utilizationcalculations are presented subsequently. The methods for managingbandwidth for each of the traffic Classes are outlined as follows:

Real Time Class Traffic Bandwidth Management:

Bandwidth for the Real Time Class is managed by the Load DistributionControl Block 1490. The Load Distribution Control Block 1490 receives anover-the-air utilization update from the Over-the-air Measurement Block1480 every measurement interval. The Load Distribution Block 1490compares this value to a set of thresholds. If any of these thresholdshave been crossed, the Load Distribution Control Block 1490 takesspecific actions, to manage the RF channel load such as moving activeSTA(s) to other APs. The details of the Load Distribution Control Block1490 are described subsequently.

For Upstream Traffic Only:

Packets which are classified as belonging to the Real Time Class may been-queued directly on the egress queues 1410 of the wired interface1460, for example Ethernet. The queue structure may follow the QoS ofEthernet IEEE 802.1p (i.e. priority queues) or of IP DiffServ as definedby IETF. The specific egress queue 1410 into which the Real Time packetis en-queued is configurable. Typically, the packet will be en-queuedinto same queue that services video packets and if there are no videopackets then it is en-queued into the same queue that services the voicepackets.

For Downstream Traffic Only:

Packets which are classified as belonging to the Real Time Class may been-queued directly on the egress queues, shown as downstream egressqueues 1430 of the Wi-Fi interface 1470 of AP 1400. The queue structuremay follow the priority of IEEE 802.11e and WMM Access Categories. Themechanism as discussed supra comprises four queues which map to theAccess Categories (AC): Voice, Video, Best Effort and Background,serviced with priority, with Voice AC being the highest priority. Thespecific queue into which the Real Time packet is en-queued isconfigurable, but is typically en-queued into the Video AC.

Data Class Traffic Bandwidth Management:

The Data Class traffic is dominated by packets using the TCP transportprotocol. TCP traffic is greedy, which means that it tries to use asmuch bandwidth as is available by opening its transmission window;however, it also has an integral congestion control mechanism. Thismeans that if a client terminal with a TCP flow detects networkcongestion, it acts to reduce the bandwidth transmitted from theterminal. A TCP session assumes network congestion is occurring when apacket timeout occurs (i.e. packet loss) or a duplicate ACK is received.At this point TCP closes a congestion window based on an algorithm whichreduces the number of packets that can be transmitted before receivingan ACK, effectively reducing the packet rate and bandwidth used.

To manage Data Class traffic, the TCP congestion control can be used asfollows. The Data Class traffic rate is controlled to match the“available over-the-air bandwidth” by using the traffic shapers 1440Aand 1440B that are inserted in the data paths between the packetclassifiers 1420 and 1450 and egress queues 1410 and 1430 in theupstream and downstream directions respectively in FIG. 14. TheOver-the-Air Measurement Block 1480 computes the utilization used byReal Time Class traffic (upstream plus downstream) and compares it tothe Configured Operating Point, or MaxTU. The difference between them isthe over-the-air utilization that is available for upstream anddownstream Data Class traffic.

Data Class over-the-air available utilization is partitioned based onconfigurable minimum ratios for downstream and upstream (e.g. 60%downstream and 40% upstream). For example, assume that MaxTU is set at90% of the AP over-the-air utilization and that Real Time Class trafficis currently using 50%. Accordingly, the upstream Data Class trafficutilization will be shaped to about 16%, being [90%−50%]*40%. Thisover-the-air utilization allocation information is sent by theOver-the-air Measurement Block 1480 to the upstream traffic shaper1440A. Updates are sent to the traffic shaper 1440A when the allocationchanges. As the traffic shaper 1440A throttles back Data Class traffic,packets are delayed or dropped and the TCP congestion control mechanismis activated to ensure the STAs throttle back to the availablebandwidth.

The traffic shaper uses its utilization allocation to manage the packetflow as follows. Utilization is calculated over a configurableMeasurement Period. Since utilization is defined by;

$\begin{matrix}{{UtilizationAllocation} = \frac{\left( {\sum\limits_{t = 0}^{t = {tmeas}}{PacketTransmissionTimes}} \right)}{MeasurementPeriod}} & (1)\end{matrix}$

where tmeas is the measurement period, the traffic shaper can determinethe allowed sum of packet transmission times over the measurementperiod. For example, if the Utilization Allocation is 16% and theMeasurement Period is 100 ms, then the allowed over-the-air sum ofpacket transmission times cannot exceed 16 ms per Measurement Period.

When the traffic shaper sends the first packet, it calculates and savesthe equivalent over-the-air transmission time. When the second packet issent it adds the transmission time to that of the first packet to createa sum. The traffic shaper continues sending packets until the sum of theequivalent over-the-air transmission times reaches the allocation. Itstops sending packets until the end of the measurement period. At thispoint, the Packet Transmission time sum is reset to zero and the aboveprocess repeats. The equivalent packet transmission time is the timeneeded to transmit a packet over-the-air with the current PHY rate forthe STA and it can be determined in several ways. For upstream frames,this information can be saved with the packet when the packet isreceived on the wireless interface. Otherwise, packet transmission timescan be recalculated using the packet size and current PHY rate for thewireless client using Equation (2) below.

The traffic shaper queue is serviced by a data rate limiting mechanismthat forwards traffic based on what over-the-air utilization is leftover from the Real Time Class. The Data Class is also configured withActive Queue Management (AQM) using algorithms such as Random EarlyDiscard (RED) for example, others being known in the prior art. AQMtechniques such as RED ensure a smooth traffic flow when packets need tobe dropped.

For Upstream Traffic Only:

Data Class packets forwarded by the traffic shaper 1440A may been-queued directly on the egress queues 1410 of the wired interface 1460(usually an Ethernet interface). The queue structure may follow the QoSof Ethernet IEEE 802.1p defined by IEEE or of IP DiffServ as defined byIETF and the specific queue into which the Real Time packet is en-queuedis configurable. Typically, the packet will be en-queued into same queuethat services best-effort packets.

For Downstream Traffic Only:

Data Class packets forwarded by the traffic shaper may be en-queueddirectly on the downstream egress queues 1430 of the Wi-Fi interface1470 of AP 1400 in FIG. 14. The queue structure may follow the QoS of802.11e or it may optionally be different for legacy devices.Accordingly, downstream packets can be classified using filter polices,and if the AP supports IEEE 802.11e then use that QoS mechanism fortraffic forwarding. Otherwise, in legacy systems, all traffic will havethe same priority but by applying a traffic shaper to data traffic,thereby delayed and rate controlling it so Real Time traffic getspriority access to over-the-air bandwidth. The mechanism includesdownstream egress queues 1430 which may map to the Access Categories:Voice (VO), Video (VI), Best Effort (BE) and Background (BG). They areusually serviced with a priority scheduler, with the Voice AC being thehighest priority. The specific queue into which the Data Class packetsare en-queued is configurable and typically Data Class packets areen-queued into the queues servicing Best Effort or Background traffic.

Bandwidth Allocation and Configuration:

Referring to FIG. 15 there is depicted a bandwidth allocation betweenclasses according to an embodiment of the invention and therefore howthe available bandwidth is allocated for each Traffic Class as well asfor upstream and downstream traffic flows. The Over-the-air Bandwidth1510 represents the configured Operating Point (MaxTA) for the RFchannel as shown in the delay curve of FIG. 12. This available bandwidthis partitioned and allocated to the Real Time Class 1520 and Data Class1530. The allocation of available over-the-air bandwidth to each trafficclass is further partitioned to upstream and downstream flows, beingupstream 1540 and downstream 1550 for Real Time Class 1520 and upstream1560 and downstream 1570 for Data Class 1530. The Real Time Classallocation is managed as a single block of bandwidth. That is the RealTime Class traffic flows are measured for both the upstream 1540 anddownstream 1550 and combined into a single over-the-air utilizationvalue. It is this combined value which is compared to the configuredguaranteed value. When the over-the-air utilization of the combinedupstream and downstream Real Time flows exceeds the guaranteed value,load distribution action is initiated and accordingly there is no needto manage traffic imbalances between upstream and downstream flows. Infact several thresholds may be used for efficient load distributionwhich is described in detail below

Since the Real Time Class gets priority service, the Data Classbandwidth allocation is what is left after the Real Time Class uses itsallocation. For example, if the Over-the-air operating point (MaxTU) isset to 90% utilization and the Real Time Class is using 50% (upstreamplus downstream), then the Data Class will be allocated the differencewhich is 40%. Furthermore, because of the greedy nature of TCP flows,Data Class traffic will try to use all the bandwidth that is available,so we need to separately assign a minimum percentage for over-the-airutilization to the upstream Data Class 1560 and downstream Data Class1570 flows. Bandwidth that is allocated to that Data Class is configuredto provide minimum bandwidth assurance as a percentage of the remainingover-the-air bandwidth for downstream and upstream. The allocations donot need to be equal and in many practical applications, the downstreamminimum percentage may have a higher allocation to account fordownloading from databases or web sites. However a minimum allocation ofbandwidth is required to assure that some packets can be sent upstreamand downstream (starvation avoidance). The allocations of upstream DataClass 1560 and downstream Data Class 1570 may be dynamically adjustedaccording to a range of predetermined thresholds or based upon thedeterminations of the data in the upstream and downstream directionsclassified by the upstream and downstream packet classifiers 1420 and1450 respectively within the AP 1400 of FIG. 14.

Interworking with IEEE 802.11e Priority:

The IEEE 802.11e priority mechanism as outlined above defines fourtraffic classes called Access Categories (AC), “Voice”, “Video”, “BestEffort” and “Background” in order of priority. Stated very simply, a STAor AP with a packet in its Voice queue has higher probability to betransmitted than a packet in one of the other queues. Higher priority isachieved by a STA using both a shorter inter-frame spacing and a shortercontention window, which combine to result in a shorter time to attemptto seize the RF channel. Frames are en-queued into a queue correspondingto its Access Category. The four queue IEEE 802.11e structure is usedfor the over-the-air interface in downstream direction, as showndownstream egress queues 1430 in FIG. 14. Within embodiments of theinvention as presented by the inventors the Real Time Class wouldtypically be mapped to the Video Access Category and the Data Class tothe Best Effort Access Category.

Traffic Shaper Description:

A traffic shaper, such as upstream and downstream traffic shapers 1480and 1440 respectively in AP 1400 are inserted in the upstream anddownstream path of Data Class packets, as separated by the upstream anddownstream Packet Classifiers 1480 and 1450 respectively, to rate limitthem so that the overall over-the-air utilization does not exceed theConfigured Average Operating Point (MaxTU). These traffic shapers can beconfigured to provide minimum bandwidth assurance for the upstream anddownstream directions through control signaling received from theOver-the-air measurement block 1480. So, for example, if the ConfiguredAverage Operating Point was 90% for over-the-air utilization with RealTime Class traffic consuming 30% then the Data Class would get thedifference or 60% of over-the-air resource to transmit packets. Further,the upstream and downstream shapers can be configured with differentweights so that upstream and downstream data throughput is differente.g. 60% downstream and 40% upstream.

Over-the-Air Measurement Block Description:

The Over-the-air Measurement Block 1480 receives inputs from theupstream and downstream Packet Classifiers 1420 and 1450 respectivelyand uses this information to calculate the over-the-air utilizations. Ituses this information together with the predetermined configuredthresholds (for example LD1, LD2, MaxTU, Upstream/Downstream ratio) tocalculate the Data Class utilization allocations which are sent to theupstream and downstream Traffic Shapers, LD1 and LD2 being two loaddistribution thresholds. The Over-the-air Measurement Block 1480 alsosends the Utilization calculations to the Load Distribution Block 1490.The calculations are made using the following process.

A: Over-the-Air Utilization Measurement:

When a packet arrives from either the Wi-Fi interface 1470 or the wiredinterface 1460, the over-the-air utilization must be calculated and isbased on Packet Transmission Time used by all upstream packets and alldownstream packets. The Packet transmission time is the duration inwhich the RF channel is seized by a STA or AP transmitting a packet. Ingeneral, this information includes the Packet Size in bytes includingthe Ethernet and IP layer headers and the PHY rate used to receive theupstream packet or the current PHY rate for downstream packets. Aformula for calculating the over-the-air time packet transmission timeis given by Equation (2)

PacketTransmissionTime=(PacketSize/PHY rate)+Overhead  (2)

where Overhead for example typically includes the sum of PHY Preamble,ACK packet time and the inter-frame spacing between the Datatransmission and the ACK packet transmission time, as defined by theIEEE 802.11 standard(s). Other equations may also be used to calculatePacket Transmission Time and in some Wi-Fi implementations, the PacketTransmission time is available from the Wi-Fi chip set.

The “Packet Transmission Time” is used to calculate the “Over-the-airUtilization” using Equation (3)

$\begin{matrix}{{UtilizationSample} = \frac{\sum{PacketTransmissionTime}}{MeasurementPeriod}} & (3)\end{matrix}$

where Packet Transmission Times are summed over a Measurement Period.The Utilization Samples are input into an exponential moving averagefilter to create damping using Equation (4)

Utilization(n)=A*UtilizationSample+(1−A)*Utilization(n−1)  (4)

where A is the averaging constant between 0 and 1, n is the samplenumber and utilization measurements are between 0% and 99% (0.0 and0.99). Measurements are made over a measurement interval which isconfigurable and typical values will range from 100 ms to 2 seconds.

Equation (4) is used to keep an ongoing running Utilization of the RealTime Class traffic which is called “Real Time Class Utilization” and theReal Time Class traffic plus Data Class traffic which is called “TotalUtilization. Accordingly, Real Time Utilization only includes PacketTransmission Times for packets determined by the Classifier as belongingto the Real Time Class whereas Total Utilization includes all packets.

B: Utilization Allocation Calculation:

The Utilization Allocations assigned to the Traffic Shapers aredetermined as follows. First calculate the over-the-air utilizationavailable for the Data Class using the Equation (5)

DataClassUtilizationAllocation=MaxTU−RealTimeUtilization  (5)

where MaxTU is a configurable parameter. If the result is negative thenset Data Class Utilization to zero. The allocations are set using thefollowing Equations (6) and (7)

UpstreamDataClassUtiliz=DataClassUtilization*UpstreamRatio  (6)

DownstreamDataClassUtiliz=DataClassUtilization*(1−UpstreamRatio)  (7)

This information is sent to the Traffic Shapers and is updated by theMeasurement Block every Measurement Period. The Measurement Block alsosends to the Load Distribution Block the Real Time Class Utilization andthe Total Utilization results (or alternatively the over-the-airutilizations for each traffic class), which are similarly updated everyMeasurement Period. This information will be used by the LoadDistribution Block 1490 as discussed below.

Session Admission and Load Distribution Control Detailed Description:

As discussed supra there are times when an AP needs to encourage a STAto roam to another AP in order to maximize the wireless system carriedload. The Load Distribution Block 1490 uses over-the-air utilizationmeasurements it receives from the Over-the-air Measurement Block 1480 todetermine when to shift associations for a STA to another AP and tomanage the actual roaming of the STA. The IEEE standards group is in theprocess of defining a protocol under 802.11v called BSS TransitionManagement whereby the AP can request that the STA roam to another AP.It uses a messaging protocol whereby an AP can initiate a request to aSTA to roam to another AP. However, this is only a part of acomprehensive load balance solution.

It is expected to take several years before this feature is introducedinto high volume consumer STAs, such as smartphones, PDAs, gamingconsoles etc and all APs. Accordingly, the inventors have developed aLoad Distribution Control solution whereby the AP, using currentlyavailable functionality, can influence the STA to roam to another AP.The solution will also work with the BSS Transition Management featurewhen it becomes available. Fundamentally, Session Admission and LoadDistribution Control (Simplified to “Load Distribution”) operates asfollows. When the Real Time Class over-the-air utilization exceeds athreshold, an attempt is made to redistribute the traffic. In fact,several thresholds of increasing over-the-air utilization can be definedand different redistribution actions taken with each being exceeded,which are increasingly more aggressive with higher thresholds because itis approaching the limit. The thresholds are defined to begin an earlydistribution of load so that the Load Distribution Block begins todistribute load before the RF channel is fully utilized (i.e. beforeMaxTU is reached). This can result in a significant improvement in totalwireless access network traffic throughput.

Referring to FIG. 16 there is depicted an example of the benefit ofpreemptive load distribution as provided by embodiments of theinvention. Consider initially first graph 1600A whereby, unless AP 2shifts some load to AP 3 before reaching channel capacity, then AP 1cannot shift any of its load to AP 2 resulting in lost traffic (thatportion above the capacity line). Load distribution, shown in secondgraph 1600B, demonstrates the resulting domino effect and increase inoverall system capacity when AP1 shift its load before reaching itscapacity limit. STAs at AP 1 may not reach AP 3 or do so with very lowsignal strength. This domino effect may involve more than 3 APs overlarger distances or within high-density environments.

Now referring to FIG. 17 there is depicted multiple thresholds fortriggering actions by an AP to improve over-the-air capacity and reducediscarded frames according to an embodiment of the invention. ThresholdLD1 defines the point at which early load distribution is invoked.Threshold LD2 defines the maximum, guaranteed level of Real Time Classtraffic. The threshold MaxTU is the maximum total traffic permitted inorder to achieve good QoS for all STAs. Accordingly LD1<LD2<MaxTU andthe difference between MaxTU and LD2, MaxTU−LD2, is the assuredutilization allocated to Data Class traffic. As outlined supra the LoadDistribution Block within an AP is responsible for making the decisionas to which threshold has been crossed and to execute the resultingrequired procedures. The Load Distribution Block is informed of the RealTime Class over-the-air utilization measurements by the Over-the-airMeasurement Block in order to make its decisions. The following areexemplary specific actions taken at each threshold:

Threshold 1: LD1 Procedures:

Threshold level LD1 is chosen to initiate early load distributionwhereby actions are taken after crossing LD1 to encourage newassociations to go to other APs that may have more availableover-the-air bandwidth. This is accomplished by reducing the channelbeacon power by a configurable amount. This action will mean that APswith more available over-the-air channel utilization will be favoured bySTAs, whereby the STAs exploit both RSSI values and other informationfor the other APs, for example including but not limited to utilizationand number of associated STAs, rather than just RSSI data. It will alsomean that more distant STAs may no longer associate with this AP, butrather will associate with APs that have a stronger beacon signalresulting in more efficient channel utilization. This will have noeffect on STAs already associated or have sessions in progress becausethe transmit power for data transmission is not reduced.

Referring to FIG. 18 there is depicted a scenario for managing APloading according to an embodiment of the invention. A portion of abuilding is shown comprising for example offices and meeting roomswithin one of which meeting 1890 there is a meeting with 16 usersassociated with it. Deployed within the building are first to third APs1820, 1830 and 1840 respectively which under normal operation have radii(simply presented assuming uniform properties of the media within thebuilding) 1860 of radius 13 meters. If the beacon power in each isreduced by 6 dB, then the effective range is reduced to one half of theoriginal, resulting in reduced radii 1850 from each AP. This results ina coverage area reduction to 25% of the original.

Clearly if all STAs undertake the same reduction then RF channelcoverage area and overlap from neighbour APs will need to be largeenough to pick up STAs. However, if only the first AP 1820 reduces itsbeacon power then users in meeting 1890 will now receive the beacon fromsecond AP 1830 at a higher level such that some or all STAs wouldassociate with the second AP 1890. Optionally, multiple LD1 thresholdsmay be employed so that first AP 1820 reduces its beacon power inmultiple steps to match the multiple thresholds. Alternatively when theLD1 threshold is crossed the beacon power of first AP 1820 is reduced inmultiple steps in order rather than a single reduction thereby reducingRF channel coverage in multiple steps.

Threshold 2: LD2 Procedures:

When the measured Real Time Class traffic utilization exceeds the LD2threshold (LD2>LD1), then additional, more forceful actions can betriggered to distribute the load. Representative actions are, the APrejects any new associations, and in addition to this encouragescandidate STAs to roam to another AP. Considering these two measuresthen:

(1) Reject New Associations: Association requests (i.e. based onreceiving an Association message) are denied by responding to anassociation request message with an association response using statuscode 17 (per IEEE 802.11-2007) which informs the STA of the following:“association denied because AP is unable to handle additional associatedSTAs”. Rejection of new associations occurs when the utilization forReal Time Class traffic is above LD2 threshold or if a predeterminedmaximum number of STA associations with the AP is reached.Re-association requests from roaming STA are also denied. Accordingly,this will prevent neighbouring APs in high load (>LD2) from forcing STAsroaming to each other in a type of infinite loop.

(2) Invoke Station Roaming: The emerging standards-based approach toforce roaming is to use the messaging and procedures defined in IEEE802.11v BSS Transition Management. As noted above this is not expectedto be available in commodity STAs (i.e. handsets, smartphones, laptops,netbooks, tablets, etc.) or low-end APs for some years. Anotherpotential approach is for the STA to be forcibly disassociated when theAP sends it a disassociate message. However, this action will mostlikely takedown any security associations and hence also any sessions(voice or video calls) that are in progress thereby abruptly terminatingthem which is not a desirable result.

As such the methods implemented according to embodiments of theinvention are intended to remove these issues whilst simultaneouslyworking with existing commercially deployed STAs, which do not supportmany of the advanced 802.11 protocols such as IEEE 802.11e, k, v, etc.Accordingly active STAs (stations that are sending or receiving data)are either influenced to move to another channel or AP by reducing theRF transmit power on the AP for only those packets that are being sentto the selected STA, i.e. the STA that is selected specifically to bemoved. The transmit RF power to other STAs is not affected. The selectedSTA therefore perceives that the distance to the AP has increased andwhen its received power level falls below a certain threshold, the STAattempts to roam to a better AP (i.e. stronger signal and/or higher PHYrate). We refer to this approach as “Implicit Load Distribution”. Whatwe term “Explicit Load Distribution” may use similar Load Distributionalgorithms (i.e. threshold definitions and actions) but the APadditionally signals using a standard messaging protocol, such as thatproposed in IEEE 802.11v or another proprietary signaling protocol,between the AP and the STA to provide additional information or controlsignals that are used by the STA to associate with another AP. Examplesof such information may include providing data relating to an AP thathas been preselected to accept the STA (for example using a controllersuch as presented supra in respect of FIG. 7).

Several criteria are used to identify which STA(s) need to be moved froma channel where the over-the-air utilization is above LD2 to a differentchannel on the same AP or neighbouring AP that is less utilized (hasmore bandwidth available) and is operating below LD2. These requiredcriteria include the following.

Station Activity:

STAs that are currently sending or receiving data are called “activestations”. Moving a STA that is not sending or receiving data to anotherAP does not reduced the over-the-air utilization and as such themechanism needs to move STA(s) that are sending or receiving data toreduce over-the-air utilization. A STA's activity is determined bymonitoring “Idle Time”, which is a client parameter that is available inmost AP implementations. Accordingly, according to an embodiment of theinvention the AP looks to see if the STA was sending or receivingnon-TCP data over a predetermined period of time, e.g. 1 second. If yes,than there is a high probability that it will send or receive non-TCPdata in the near future and therefore this STA will contribute toover-the-air utilization on the channel or AP. Moving that STA toanother channel or AP will reduce the over-the-air utilization on thatchannel or AP. Equally, if the STA whilst included within the analysisstops transmitting, this would have the same impact as if STA was moved,namely the over-the-air utilization is reduced.

PHY Rate:

This is the data rate that is currently used to send and receivedpackets between the STA and the AP. It will be one of the supported datarates that both the STA and AP supports and was selected based oncurrent SNIR (Signal to Noise and Interference Ratio). Valid entriesData Rate are 1 though 600:

802.11b, 1, 2, 5.5, 11;

802.11a/g, 6, 9, 12, 18, 24, 36, 48, 54;

802.11n data rates;

1×1 20 Mhz Ch. 6.5, 13, 19.5, 26, 39, 52, 58.5, 65;

1×1 40 Mhz Ch. 13.5, 27, 40.5, 54, 81, 108, 121.5 135;

1×1 40 MHz Ch. Short Guard Interval, 15, 30, 45, 60, 60, 120, 135, 150;

2×2 20 MHz Ch. 13, 26, 39, 52, 78, 104, 117, 130;

2×2 40 MHz Ch. 27, 54, 81, 108, 162, 216, 243, 270;

2×2 40 MHz Ch. Short Guard Interval, 30, 60, 90, 120, 180, 240, 270,300;

3×3 20 MHz Ch. 19.5, 39, 58.5, 78, 117, 156, 175.5, 195;

3×3 40 MHz Ch. 40.5, 81, 121.5, 162, 243, 324, 364.5, 405;

3×3 40 MHz Ch. Short Guard Interval, 45, 90, 135, 180, 270, 360, 405,450;

4×4 20 MHz Ch. 26, 52, 78, 104, 156, 208, 234, 260;

4×4 40 MHz Ch. 54, 108, 162, 216, 324, 432, 486, 540;

4×4 40 MHz Ch. Short Guard Interval, 60, 120, 180, 240, 360, 480, 540,600.

Real Time Traffic:

STAs that are sending non-TCP packets are candidates to be moved toanother channel or AP. Station Roaming Value (SRV) is calculated foractive STAs that were sending/receiving non-TCP packets in the past onesecond. The table is checked if the entry is not a TCP flow to indicatethat this is a candidate to be moved.

RSSI:

Receive signal strength indicator (RSSI) is a measurement of the powerpresent in a received radio signal. The RSSI is a parameter that has avalue of 0 through RSSI Max (up to 255). This parameter is measured bythe PHY layer based on the energy observed at the receiver, oralternatively the antenna, when receiving the current Physical LayerConvergence Protocol (PLCP) Protocol Data Unit (PDU). RSSI is measuredbetween the beginning of the Start Frame Delimiter, an 8-bit valuemarking the end of the preamble of an Ethernet frame and the end of thePLCP Header Error Check (HEC), a 16-bit Cyclic Redundancy Check that iscalculated over the contents of the header of the Ethernet frame andinserted into the header. RSSI is intended to be used in a relativemanner and hence the absolute accuracy of the RSSI reading is notimportant, and different AP vendors may use slightly different methods.The received signal strength at the STA is not known but it isreasonable to assume a symmetric RSSI because the transmission path isoften the same for traffic in both directions. If the two RSSI valuesare somewhat different, it will have minimal impact on the algorithmperformance It would be evident to one skilled in the art thatalternatively Received Channel Power Indicator (RCPI), which is measuredacross the entire frame rather than the preamble, may be employed.

Error Rate:

Receive bit error rate is a whole number between 0 and 100 and is apercent value.

Station Priority:

This parameter is used to indicate priority for roaming and that the STAwas selected for roaming, and normally the default value for StationPriority is set to zero. When a STA was selected for roaming but did notroam, a predetermined value, e.g. 50 is added to the Station Priorityvalue. When a STA successfully completes roaming its Station Priority isreset to the configured value. Increasing the SRV value reduces theprobability that this STA will be asked to roam again soon so that theprocess does not waste time repeatedly trying to force a STA to roamthat cannot.

TABLE 1 Station Statistics Table MAC Real- PHY Error Station AddressIdle Time time Rate RSSI Rate Priority SRV

These parameters are stored by the AP in a table, such as shown in Table1 above, and are updated at a predetermined rate, for example everysecond. When the over-the-air Utilization exceeds LD2 for Real TimeClass traffic, the AP scans through its table of associated STAs withIdle Time less than the predetermined value, e.g. 1 second, and computesthe Station Roaming Value (SRV). An exemplary algorithm for SRV beingshown in Equation (8).

SRV=A*PHY+B*RSSI+C*(100−ErrorRate)+StnP  (8)

where A, B, C are configurable weight factors and StnP is StationPriority.

A STA is selected based on the smallest value of the Station RoamingValue (SRV). An exemplary algorithm of “Implicit Load Distribution” isshown by the flowchart in FIG. 19 and starts at step 1910. In step 1920a determination is made whether the over-the-air utilization for RealTime Class traffic exceeds the LD2 threshold. If not then the flow movesto step 1930, waits for a predetermined period, before looping back tostep 1910. If the LD2 threshold has been met or exceeded then the APscans the Station Statistics Table in step 1940 to identify any STA thathas an Idle Time that meets a predetermined duration and computes aStation Roaming Value (SRV) for each identified STA.

Next in step 1945 the AP selects a STA from all STAs associated with theAP with the smallest Station Roaming Value. A STA with the smallest SRVvalue has the most inefficient use of over-the-air resources. Since theformula for SRV is comparing over-the-air receive conditions betweenSTAs, the exact method used for computing RSSI and Error Rate is notimported because our algorithm looks at the difference between STAs. Thealgorithm now proceeds to step 1950 wherein it applies the powerreduction procedure to the frame transmission for the identified STA toforce it to roam to an adjacent AP.

An exemplary procedure for the power reduction formula is as follows.Reduce the transmit power from the AP to only the selected STA so thatSTA's receive signal is below the level where the STA invokes itsroaming procedure (i.e., −72 dBm) for a short period of time (i.e. 3seconds). To determine the amount the AP needs to reduce it's transmitpower to the selected STA, the AP measures the receive power from theSTA and computes the difference between current measured level and −72dBm and reduces the transmit power by that amount. In typicalimplementations, the AP measures Received Signal Strength Indicator(RSSI) using a proprietary scale. Therefore, a RSSI value to dBmequivalency for −20 dBm to −90 dBm range needs to be determined for eachvendor's AP that this algorithm is implemented on. The process movesthen to step 1960 wherein a wait is executed and a determination is madeas to whether the STA has roamed to another AP. If the STA has notroamed then a predetermined value is added to its Station Priority, instep 1970, this Station Priority forming part of the data used tore-calculate the SRV and RF power for frame transmissions to this STA isrestored back to normal. The flow then returns to step 1945 and retrieswith the next best STA candidate.

If the disassociation of the STA was successful then the process waitsfor a predetermined time shown in step 1980, before returning to step1920 to determine if the over-the-air utilization has dropped below LD2.If not, the flowchart reapplies the process to redistribute another STA.Whilst the process in respect of FIG. 19 was described in respect of asingle STA it would be evident that the process may optionally seek todisassociate a number of STAs to reduce the over-the-air utilization. Itwould be evident to one skilled in the art that the selection, by theAP, of the STA(s) that will have the RF power reduced duringtransmissions to it to try and force the disassociation. It would beapparent to one skilled in the art that the received signal powerthreshold and wait duration may be predetermined values or that thesemay be established dynamically according to factors determined by the APor the network and communicated to the AP.

Threshold 3: MaxTU Procedures: The MaxTU (Total Utilization) thresholdis the maximum utilization for sum of Real Time Class traffic and DataClass traffic. When the aggregate (Real Time Class and Data Class)utilization exceeds, MaxTU, the engineered limit for the over-the-airutilization, then extreme measures need to be taken to maintain servicequality because load distribution and rate control measures wereinadequate. The MaxTU procedures include forcing a disassociation of aSTA(s) such that the STA(s) will then begin the procedure forre-associating to an alternate STA. An exemplary procedure for forceddisassociation may, for example, begin with the AP determining which STAto drop using the procedures described above in respect of Threshold 2:LD2 Procedure with the modification that any traffic can bedisassociated irrespective of whether the traffic is TCP or non-TCP.Once the STA(s) has been selected the AP sends a disassociation messageand does not reduce RF transmit power for the STA(s). For example, theAP sends a disassociate message using reason code 5 (per IEEE802.11-2007) that informs the STA of the following: “Disassociatedbecause AP is unable to handle all currently associated STAs”. If thedisassociated STA does not find another STA and tries to return to thisAP then the association request is rejected while at this thresholdlevel.

Operation with Multiple BSS:

Within the scenarios discussed supra there has been an implicitassumption that the AP is operating as a single BSS. However, in manysituations an AP may support multiple BSS cells. The embodiments of theinvention described supra for Admission and Load Distribution Controlwill operate within these scenarios as discussed below.

Consider, for example, the scenario of a school where the Wi-Fi channelshave been subdivided into two BSS: one for teachers and one forstudents. Two sets of thresholds are therefore defined, one for eachBSS. If the students exhaust their over-the-air utilization (sayMaxTU1), this will have no effect on the teachers' assigned over-the-airutilization. Therefore, new student sessions will beblocked/disassociated but the teachers can continue to make new callsassuming they have available over-the-air utilization allocation.According to embodiments of the invention there are two over-the-airutilization partitioning models considered, Dedicated and Shared. Theprinciples of Admission and Load Distribution will work with multipleBSS using each partitioning model.

Dedicated Partitioning Model:

An exemplary implementation for multiple thresholding for triggeringactions by an AP to improve over-the-air capacity and reduce discardedframes for according to an embodiment of the invention wherein there aretwo BSS's per channel is depicted in FIG. 21 according to an embodimentof the invention. In this model the over-the-air utilization is dividedinto two fixed partitions, BSS1 and BSS2 that are associated with firstand second BSS respectively. The MaxTU threshold still needs to becalculated for the AP as it represents a system maximum but now whenmultiple BSS are deployed from the same AP the MaxTU is divided andallocated to the BSS as MaxTU(n) where n is the partition number and

${{Max}\; {TU}} = {\sum\limits_{1}^{n}{{Max}\; {{{TU}(n)}.}}}$

The partitions do not have to be equal or even related in any manner toone another other than their sum cannot exceed MaxTU. For example, ifMaxTU is 90% and there are two BSS in use, then a possible allocationcould MaxTU(1)=20% and MaxTU(2)=70%. Similarly, LD1(n) and LD2(n) can becalculated to fit into their max MaxTU(n) allocation such that

LD1(n)<LD2(n)<MaxTU(n)  (8)

Accordingly, the Packet Classifiers, such as Upstream and DownstreamPacket Classifiers 2220 and 2225 respectively in AP 2200 of FIG. 22,according to an embodiment of the invention, have to determine for eachpacket not only which Traffic Class the traffic belongs to based onheader fields but also which BSS it belongs to based on BSS informationwithin the frame. This information is sent to the Over-the-airMeasurement Block 2230 in addition to the BSS number, n, to which itrelates. The Over-the-air Measurement Block 2230 now also keeps track ofthe thresholds for each BSS which include LD1(n), LD2(n) and MaxTU(n),where n is the BSS number. The previously outlined formulas for theOver-the-air Measurement presented supra are now applied for each BSS.The Over-the-air Measurement Block 2230 uses the information collectedfrom the Upstream and Downstream Packet Classifiers 2220 and 2225respectively and the provisioned Thresholds to determine theover-the-air utilization allocations for the Data Class for each BSS.

Within the AP 2200 of FIG. 22 there are depicted two Traffic Shapers2240 per BSS (one per BSS in each of the upstream and downstreamdirections). The Over-the-air Measurement Block 2230 sends to theTraffic Shapers 2240 its over-the-air utilization allocation for theirrespective BSS. Each Traffic Shaper 2240 then shapes the traffic for itsrespective BSS and sends the packets to the appropriate queues in theWired interface 2250 and Wireless interface 2255 respectively for theupstream and downstream directions. As depicted the Traffic Shapers 2240output to the same interface queue 2260 although it would be evident toone of skill in the art that each Traffic Shaper 2240 may output to adifferent interface queue 2260.

The Over-the-air Measurement Block sends to the Load Distribution Blockthe traffic class utilization per traffic class for each BSS. The LoadDistribution Block uses the over-the-air utilization information andthreshold levels for each BSS to determine if a threshold has beencrossed. If a threshold has been crossed then, the Load DistributionBlock 2270 begins the appropriate procedures as defined supra to managethe traffic load but only for the affected BSS. All tables and datastructures are replicated for each BSS. Accordingly, the traffic ismanaged independently for each traffic class in both the upstream anddownstream directions for multiple BSS's within a single AP withoutrequiring any upgrade to the STAs it supports.

Shared Partition Model:

Now referring to the Shared Partition Model, depicted by the model inFIG. 23, according to an embodiment of the invention, wherein multiplethresholding for triggering actions by an AP to improve over-the-aircapacity and reduce discarded frames according to an embodiment of theinvention is depicted wherein the AP supports multiple BSS's. The SharedPartition Model is more efficient than the Dedicated Partition Model.Essentially each BSS gets some “Guaranteed” bandwidth allocation foreach of the Real Time and Data classes but there is also a “Shared”bandwidth portion. This reduces the level of stranded bandwidth andincreases the over-the-air bandwidth usage efficiency. Strandedbandwidth is bandwidth not used by one BSS, but reserved for it that isnot available to another BSS. Referring to FIG. 23 the original RealTime Class is now partitioned into a BSS1 RT Allocation and a BSS2 RTAllocation. Similarly the original Data Class is now partitioned into aBSS1 D Allocation and a BSS2 D Allocation. There is also a SharedAllocation which can be used by any of the traffic classes according tothe defined usage rules, an exemplary scenario being presented below.

Similarly, the Data Class traffic can use the Real-time allocation asdescribed supra for the single BSS scenario. The Data Class traffic canuse the Share Allocation if it is not used by the Real Time Class. TheData Class Allocation is split between the BSS's to maintain the ratioof BSS1-Allocation:BSS2-Allocation, see FIG. 15. Optionally theallocation between BSS1 and BSS2 in the Data Class may be allocateddifferently. The Real Time Class traffic has priority over the DataClass in being able to use the Share Allocation. BSS1 Real-time Classand BSS2 Real-time Class traffic use the Share Allocation in a FirstCome First Session manner without any need to maintain the BSS1:BSS2ratio although optionally this may be enforced. The Over-the-airMeasurement Block 2230 ensures the Real Time Class gets priority whichit does by providing the Traffic Shapers 2240 with their allocations toensure Data Class backs off as Real Time traffic increases.

Typically, a single MaxTU threshold is employed for each channel on anAP. When the over-the-air utilization exceeds this level, the MaxTUprocedures are applied by the AP. Similarly, each channel typicallyoperates with a single LD2 threshold shown in FIG. 23. The LD2 thresholdis deemed crossed when the Share Allocation is exhausted. When thishappens, the AP 2200 determines that at least one BSS has exhausted itsReal Time allocation and its guaranteed allocation. If one BSS of aplurality of BSSs has exhausted its guaranteed allocation, then the LD2procedures are applied to that BSS. If all supported BSSs have exhaustedtheir guaranteed allocation then the LD2 procedures are applied to allBSSs equally and alternately. These procedures being discussed supra inrespect of LD2 for a single BSS.

In one scenario, according to an embodiment of the invention, there is asingle LD1 threshold for an AP channel. The LD1 threshold would beconfigured within the Shared Allocation. If a BSS's over-the-air channelutilization exceeds the LD1 threshold, then the LD1 procedures areapplied to that BSS. If multiple BSSs exceed the LD1 threshold, then theLD1 procedures are applied to these BSSs equally and alternately. Inanother scenario there is one LD1 threshold for each BSS where theLD1(1) threshold is configured within the guaranteed allocation of BSS1and the LD1(2) threshold is configured within the guaranteed allocationof BSS2 and so on for BSSn. Then the LD1 procedures are applied to theBSS that cross their LD1 threshold. These procedures being discussedsupra in respect of LD1 for a single BSS.

It would be evident to one skilled in the art that the examples providedsupra in respect of a shared partition of multiple BSSs to a common APchannel can be implemented without departing from the scope of theinvention. Some examples include making the Data Class non-partitionedin a manner similar to the Shared Allocation, the Shared Allocation mayhave a limit to the percentage one BSS, the thresholds may bedynamically established, the settings for a BSS may be set to low orhigh percentages.

Coexistence with Standards-Based Admission Control:

As discussed previously the exemplary embodiments of the invention areintended to simultaneously operate with IEEE 802.11 STAs that have orhave not implemented the evolutions of IEEE 802.11 captured in IEEE802.11e, k, v, etc., including those aspects of the standards basedAdmission Control using the IEEE 802.11e Tspec (Traffic Specification).We refer to this as coexistence, by which we mean some wireless STAswill use the embodiments of the invention and that other wireless STAswill use the standards based solution at the same time. There arebelieved to be no interworking issues between the two solutions. Thiscoexistence is shown in FIG. 22 by first and second legacy clientstations STA1 and STA N 2210A and 2210C respectively that form part of aBSS with AP 2200 at the same time as an 802.11e compliant client stationSTA 1 2210B.

Considering how coexistence functions, then in general, thestandards-based Admission Control in IEEE 802.11e standard is based uponthe four priority traffic classes: Voice (VO), Video (VI), Best-Effort(BE) and Background (BG) which are listed from highest to lowestpriority. A STA sends a message to the AP to request bandwidth in aparticular traffic class and the requested traffic characteristics arerecorded in the Tspec which is appended to the request message. If theAP has over-the-air utilization allocation available, then the AP willsend a reply to admit the session. Otherwise, the AP may deny therequest.

TABLE 2 Traffic Class Mapping of IEEE 802.11e to Invention Traffic Classof IEEE 802.11e Access Embodiments of Invention Categories Data ClassBest Effort Background Real Time Class Voice Video

Co-existence needs a mapping between the traffic classes, such as thatshown above in Table 2 for the two traffic classes defined in thisspecification according to embodiments of the invention. It would beevident that other mappings would be possible as well as consideringmore data classes. The work to ensure proper co-existence is done in thePacket Classifier, or optionally a separate block that monitors headerdata. Traffic which uses Access Categories will be marked with thesecategories in the header frames. For example, a frame that was sentusing Access Category “Video” will have its AC field in the QoS headermarked accordingly. The Packet Classifier will need to identify theAccess Category if it was applied to the transmission and will thenperform the mapping from the Access Category to the Network Classesdefined, i.e. Data Class and Real Time Class. When the Packet Classifierpasses the frame information to the Measurement Block, it will send themapped information. For example, the Packet Classifier would map a VideoAccess Category packet to Real Time Class. It will then send the frameinformation to the Over-the-air Measurement Block including the TrafficClass as being the Real Time Class. Because of the mapping all otherfunctions would operate with no changes required within the AP.

The recommended mappings of the IEEE 802.11 Access Categories to the3invoa Networks Classes are as follows. The Voice Access Category andthe Video Access Category are mapped to the Real Time Class because theyboth represent interactive Real Time traffic which typically uses UDPfor transport. These traffic types have similar Quality of Servicerequirements in terms of delay, loss and jitter. The Best-Effort AccessCategory and Background Access Category map to the Data Class. They havesimilar Quality of Service requirements and they typically use TCP fortransport.

Adjacent-Channel-Interference Mitigation Detailed Description:

Adjacent channel interference occurs when two wireless STAs are inproximity to each other, each STA is using a different RF channel andeach STA has active (transmitting and receiving packets) sessions. Thisscenario can occur for many reasons including people using multiplewireless devices such as a laptop and Smartphone with both being activeat the same time e.g., person at their desk is talking on Smartphonewhile their laptop is sending or receiving a file. Due to one or morereasons, including but not limited to mobility, load balancing, etc,these devices are connected to different APs or different RF channels onthe same AP. Another scenario is two people with laptops or otherwireless devices who are in close (less than 3 meters) proximity to eachother having arrived at this proximity from different directions so thatthey are connected to different APs.

Referring to FIG. 20 there is depicted a deployment scenario and theresulting interference arising therefrom from such events that isaddressed by an embodiment of the invention. Consider two STAs, STA12020 and STA2 2030, which are each associated with a different AP, AP12010 and AP2 2040 respectively and having an active session. If STA12020 is transmitting on channel 6 to AP1 2010, for example, then themain lobe of spectral energy emission will be around 2.437 GHz and atabout −18 dBm at station 2 (Station 1 and 2 are close together ˜20centimeters apart). The specification for the transmit filter of IEEE801.11a/b/g/n transmitters is such that some resulting spectral energywill be emitted far outside of the channel 6 region. Now consider STA22030, which is receiving packets from AP2 2040 on channel 1 at 2.412 GHzand accordingly the received signal strength is relatively low, around−62 dBm.

As evident from FIG. 20 the stray energy from channel 6 is interferingwith the received signal on channel 1 at STA2 2030, this stray energybeing at about −73 dBm for this example. This will result in a reductionin the signal-to-noise-and-interference ratio (SNIR) which in turnresults in a reduction of the PHY rate. For example the PHY rate at STA2may drop from 54 Mb/s to 6 Mb/s, which is a significant reduction inthroughput and efficiency thereby significantly lengthening a filetransfer time. The interference may in other scenarios be sufficientlysevere so as to completely block reception. Of course, the scenario mayoccur in reverse where STA1 is receiving and STA2 is transmitting.

It is therefore necessary, in seeking to address over-the-airutilization and network efficiency to establish a solution for thisinterference. At present within IEEE 802.11 and other prior artreferences the solutions are focused to network design by establishingAP locations, transmitted powers, and channel allocations are computedin order to obtain the best RF coverage at the same time that thesufficient capacity is provided, see for example “Large-Scale WirelessLAN Design” by A. Hills (IEEE Comms Magazine, Vol. 39, No. 11, pp.98-107, November 2001) and “On the Design and Capacity Planning of aWireless Local Area Network” by R. C. Rodrigues et al (NetworkOperations and Management Symposium, NOMS, pp. 335-348, April 2000). Indense deployments, however, additional developments are reported such asenhanced channel planning see for example “New Algorithm for DistributedFrequency Assignments in IEEE 802.11” by E. Garcia Villegas et al(European Wireless 2005), adjusting network configuration such asreported by Aruba Networks with their Adaptive Radio Management removesome APs and establish them as Air Monitors in their terminology, andreducing the output power of the APs and communicating backoff valuesbetween the APs to help determine the levels for other APs to backoff,see for example U.S. Pat. No. 7,366,537 entitled “Wireless NetworkApparatus and System”. These techniques presented supra with respect tothe prior art seek to address Co-Channel Interference in the wirelessnetwork or Adjacent Channel Interference in AP implementation with tworadios. The approaches as described according to embodiments of theinvention address Adjacent Channel Interference between STAs (STAs thatare in close proximity of each other but are on different channels).

In contrast, the inventors have established an alternate strategyaccording to embodiments of the invention by moving the affected STA onto different channel, preferably on the same channel that the other STAis using. According to an embodiment of the invention detection thatinterference is occurring is made by the AP by comparing the receivesignal strength from the STA to the actual PHY rate with the STA. If thePHY rate is too low for the received signal strength, then interferenceincluding Adjacent Channel Interference is likely present resulting inan increased bit error rate at the STA, i.e. low SNIR. The high errorrate will result in the Wi-Fi radios of STAs experiencing interferencereducing their PHY rate to a point where errors are eliminated. Forexample, if the receive power level is >−65 dBm and transmission DataRate is less than minDataRate (802.11a/g, 24 Mbps; 802.11n 1×1 MIMO, 26Mbps, 2×2 MIMO 52 Mbps, 3×3 MIMO 78 Mbps, and 4×4 MIMO 104 Mbps;802.11b, 5.5 Mbps) then the SNIR is less than 16 dB because the STA isexperiencing significant RF interference. To achieve high PHY data ratesa SNIR of 28 dB or higher is required.

Having determined that interference is occurring embodiments of theinvention attempt to resolve this by encouraging one of the STAsexperiencing interference to move to another AP or RF channel using thetechniques described above in respect of “Invoke Roaming” for theaffected STA(s). Ideally, the roam should result in the two STAs beingconnected to the same AP or RF channel. Given the typical closeproximity of the STAs experiencing interference, and assuming sufficientbandwidth is available, this is a likely outcome after roaming. Asdescribed above the reason that two STAs may be associated withdifferent channels is that the connections were made at differentlocations and the STAs were physically moved into sufficient proximityfor the interference to result whilst maintaining their originalassociations.

Exemplary basic algorithms according to embodiments of the inventionfollow the flow charts 2400 and 2450 in FIG. 24. It would be apparent toone skilled in the art that by applying transmit power reductionprocedure defined supra to invoke STA to roam does not require anyadditional capability over what is in the IEEE 802.11-2007specification. By contrast, the signaling approach requires a signalingmethod between AP and the STA to pass additional traffic managementinformation where by AP can request STA to invoke roaming.

As a background process, a software operational task in steps 2405 runsperiodically, say every n seconds, in the AP scanning through theStation Statistics Table looking for active STAs in steps 2410 that haveRSSI greater than some threshold (i.e., RSSI>−65 dBm). For the nextstep, the AP checks if the PHY data rate is too low for the signalstrength (Method A 2400 step 2415) or checks if the receiver Error Rateis too high for the RSSI (Method B 2450 step 2430). On encountering aSTA that meets the above criteria, the AP applies the transmit powerreduction procedure to force the STA to roam to an adjacent AP in steps2420. If after a timeout, i.e. 3 seconds, the STA does not roam away,then the AP restores RF power back to normal power level (not shown forclarity) and returns to steps 2405. Alternatively in steps 2420, the APmay also use Explicit Signaling in which case, the AP signals to theselected STA using the 802.11v standardized protocol or using aproprietary signaling roaming request with optionally specifying thechannel/AP with which the selected STA should re-associate. Theprocedure then waits again in step 2425, i.e. 3 seconds, for the valuesin the Station Statistics Table to get updated and the procedurescontinues from the beginning in steps 2405 looking for additional STAsthat are experiencing Adjacent Channel Interference.

It would be apparent to one skilled in the art that the determination ofadjacent channel interference through PHY or receiver error ratediscussed supra in respect of determining whether to trigger a roamingprocedure may also be made by the STA as described below in respect offlow charts 2500 and 2550 in FIG. 25 and that the threshold for RSSI maybe established at other values than −65 dBm as described supra inrespect of FIG. 24. The exemplary algorithms for Adjacent ChannelInterference Mitigation in the STA closely follow the Adjacent ChannelInterference Mitigation algorithms for the AP. The following are thesalient differences. Firstly the STA only needs to test its own RSSIlevel, PHY rate and error rate to make a decision on whether to roam anddoes not need any other information relating to the BSS to which it iscurrently joined. Further, the STA performs its own roaming byperforming a channel scan, selecting the best channel and then followsclient procedures to disassociate with the current AP and re-associatewith the selected AP. If the STAs and APs both support signaling, forexample to the 802.11v protocol or a vendor specific signaling protocol,then on detection of adjacent channel interference, the STA may signalinformation (its performance parameters) to the AP and then the APinstructs the STA to roam to the same channel that the closely locatedneighbour STA is using. Beneficially the STA does not need to waitbefore performing the next check, as it knows with certainty whether ifit has roamed or not.

As presented supra solutions to the management of QoS for WLANsaccording to embodiments of the invention are based upon the addition ofnew functionality added to the network, e.g. the APs or theircontrollers, and not the client stations (STAs). This functionalityconsisting of several components which have been discussed supra, namelyVirtual Station Priority; Session Admission Control; Load DistributionControl; together with Adjacent Channel Interference Control that areimplemented in varying combinations according to embodiments of theinvention.

The methodologies described herein are, in one or more embodiments,performable by a machine which includes one or more processors thataccept code segments containing instructions. For any of the methodsdescribed herein, when the instructions are executed by the machine, themachine performs the method. Any machine capable of executing a set ofinstructions (sequential or otherwise) that specify actions to be takenby that machine are included. Thus, a typical machine may be exemplifiedby a typical processing system that includes one or more processors.Each processor may include one or more of a CPU, a graphics-processingunit, and a programmable DSP unit. The processing system further mayinclude a memory subsystem including main RAM and/or a static RAM,and/or ROM. A bus subsystem may be included for communicating betweenthe components. If the processing system requires a display, such adisplay may be included, e.g., a liquid crystal display (LCD). If manualdata entry is required, the processing system also includes an inputdevice such as one or more of an alphanumeric input unit such as akeyboard, a pointing control device such as a mouse, and so forth. Theterm memory as used herein refers to any non-transitory tangiblecomputer storage medium.

The memory includes machine-readable code segments (e.g. software)including instructions for performing, when executed by the processingsystem, one of more of the methods described herein. The software mayreside entirely in the memory, or may also reside, completely or atleast partially, within the RAM and/or within the processor duringexecution thereof by the computer system. Thus, the memory and theprocessor also constitute a system comprising machine-readable code.

In alternative embodiments, the machine operates as a standalone deviceor may be connected, e.g., networked to other machines, in a networkeddeployment, the machine may operate in the capacity of a server or aclient machine in server-client network environment, or as a peermachine in a peer-to-peer or distributed network environment. Themachine may be a computer, a set-top box, a cellular base station, awireless device, a web appliance, a network router, switch or bridge, orany machine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. The term“machine” may also be taken to include any collection of machines thatindividually or jointly execute a set (or multiple sets) of instructionsto perform any one or more of the methodologies discussed herein. Theabove-described embodiments of the present invention are intended to beexamples only. Alterations, modifications and variations may be effectedto the particular embodiments by those of skill in the art withoutdeparting from the scope of the invention, which is defined solely bythe claims appended hereto.

1. A method comprising: (a) providing an access point supporting atleast a communication session of a plurality of communication sessions,each communication session associated with a client station of aplurality of client stations operating according to a firstpredetermined standard and comprising a plurality of frames, the accesspoint comprising a first receiver operating according to a secondpredetermined standard, a first transmitter operating according to athird predetermined standard, an over-the-air measurement block, a loaddistribution control block, and a processor; (b) determining with theover-the-air measurement block for each communication session at leastone load utilization of a plurality of load utilizations, each loadutilization associated with at least a predetermined traffic class of aplurality of traffic classes; (c) determining with the processor foreach traffic class an accumulated load utilization in dependence upon atleast the plurality of load utilizations relating to the plurality ofcommunication sessions associated with that traffic class; (d)determining with the processor whether a predetermined threshold of aplurality of thresholds has been exceeded, the predetermined thresholdrelating to a predetermined traffic class or a plurality of trafficclasses; and (e) triggering an action of a plurality of actions by theload distribution control block when the determination is that apredetermined threshold of the plurality of thresholds has beenexceeded.
 2. The method according to claim 1 wherein, the plurality ofclient stations form a basic service set (BSS) with the access point orthe plurality of client stations form a BSS with the access point andare one BSS of a plurality of BSSs supported by the access point,wherein the total available bandwidth of the access point is partitionedand allocated to the plurality of BSSs according to a predeterminedallocation model that defines allocations for each traffic class of theplurality of traffic classes for each BSS of the plurality of BSSs. 3.The method according to claim 1 wherein, triggering an action comprisesat least one of selectively reducing to a first predetermined level theoutput power of the first transmitter beacon transmissions; anddetermining a predetermined subset of client stations of the pluralityof client stations in dependence upon at least one of a characteristicof each communication session of the plurality of communication sessionsand a characteristic of each client station of the plurality ofstations; and at least one of selectively reducing to a firstpredetermined level the output power of the first transmitter fortransmissions for frames intended only for each station within thepredetermined subset of client stations and signaling each stationwithin the predetermined subset of client stations according to a fourthpredetermined standard.
 4. The method according to claim 3 wherein, acharacteristic of each communication session is at least one of a clientstation score, a measure of frame transmission rate, a measure ofreceived signal strength, frame error rate; and a characteristic of eachclient station is at least one of a client station roaming priority, anidentity associated with a client station, and an indication of mobilityof a client station.
 5. The method according to claim 3 wherein,signaling comprises signally at least one of an indication of a channelaccording to the second standard for the second device to operate upon,an indication of an identity of another access point with which theclient station should initiate a second communication session, and anindication for the client station to invoke a roaming procedure.
 6. Themethod according to claim 1 wherein, triggering an action comprises;determining a predetermined subset of client stations of the pluralityof client stations in dependence upon at least one of a characteristicof each communication session of the plurality of communication sessionsand a characteristic of each client station of the plurality ofstations; and terminating the communication sessions associated with thepredetermined subset of client stations by signaling each client stationof the predetermined subset of client stations according to a fourthstandard with a message to disassociate from the access point.
 7. Themethod according to claim 1 further comprising; (f) maintaining theaction for a predetermined number of transmissions; and (g) determiningby repeating steps (b), (c) and (d) whether the predetermined thresholdis still exceeded; wherein if the predetermined threshold is now notexceeded terminating the triggered action; and if the predeterminedthreshold is still exceeded determining whether to at least one oftrigger another action of the plurality of actions, maintain thetriggered action of the plurality of actions, and adjust an aspect ofthe triggered action of the plurality of actions.
 8. The methodaccording to claim 1 wherein, at least one of the first and secondpredetermined standards are selected from the group comprising IEEE802.11, IEEE 802.15, IEEE 802.16, IEEE 802.20, UMTS, GSM 850, GSM 900,GSM 1800, GSM 1900, GPRS, ITU-R 5.138, ITU-R 5.150, ITU-R 5.280, andIMT-2000.
 9. A device comprising: a first receiver operating accordingto a first predetermined standard capable of supporting at least acommunication session of a plurality of communication sessions, eachcommunication session associated with a client station of a plurality ofclient stations operating according to a first predetermined standardand comprising a plurality of frames; a first transmitter operatingaccording to a second predetermined standard; an over-the-airmeasurement block; a load distribution control block; a non-transitorytangible computer readable medium encoding a computer process; and aprocessor for executing the computer process, the computer processcomprising: (a) determining with the over-the-air measurement block foreach communication session at least one load utilization of a pluralityof load utilizations, each load utilization associated with at least apredetermined traffic class of a plurality of traffic classes; (b)determining with the processor for each traffic class an accumulatedload utilization in dependence upon at least the plurality of loadutilizations relating to the plurality of communication sessionsassociated with that traffic class; (c) determining with the processorwhether a predetermined threshold of a plurality of thresholds has beenexceeded, the predetermined threshold relating to a predeterminedtraffic class; and (d) triggering an action of a plurality of actions bythe load distribution control block when the determination is that apredetermined threshold of the plurality of thresholds has beenexceeded.
 10. The method according to claim 9 wherein, the plurality ofclient stations form a basic service set (BSS) with the access point orthe plurality of client stations form a BSS with the access point andare one BSS of a plurality of BSSs supported by the access point,wherein the total available bandwidth of the access point is partitionedand allocated to the plurality of BSSs according to a predeterminedallocation model that defines allocations for each traffic class of theplurality of traffic classes for each BSS of the plurality of BSSs. 11.The method according to claim 9 wherein, triggering an action comprisesat least one of selectively reducing to a first predetermined level theoutput power of the first transmitter beacon transmissions; anddetermining a predetermined subset of client stations of the pluralityof client stations in dependence upon at least one of a characteristicof each communication session of the plurality of communication sessionsand a characteristic of each client station of the plurality ofstations; and at least one selectively reducing to a first predeterminedlevel the output power of the first transmitter for transmissions forframes intended only for each station within the predetermined subset ofclient stations and signaling each station within the predeterminedsubset of client stations according to a fourth predetermined standard.12. The method according to claim 11 wherein, a characteristic of eachcommunication session is at least one of a client station score, ameasure of frame transmission rate, a measure of received signalstrength, frame error rate; and a characteristic of each client stationis at least one of a client station roaming priority, an identityassociated with a client station, and an indication of mobility of aclient station.
 13. The method according to claim 11 wherein, signalingcomprises signally at least one of an indication of a channel accordingto the second standard for the second device to operate upon, anindication of an identity of another access device with client stationshould initiate a second communication session, and an indication forthe client station to invoke a roaming procedure.
 14. The methodaccording to claim 9 wherein, triggering an action comprises;determining a predetermined subset of client stations of the pluralityof client stations in dependence upon at least one of a characteristicof each communication session of the plurality of communication sessionsand a characteristic of each client station of the plurality ofstations; and terminating the communication sessions associated with thepredetermined subset of client stations by signaling each client stationof the predetermined subset of client stations according to a fourthstandard with a message to disassociate from the access point.
 15. Themethod according to claim 9 further comprising; (e) maintaining theaction for a predetermined number of transmissions; and (f) determiningby repeating steps (a), (b) and (c) whether the predetermined thresholdis still exceeded; wherein if the predetermined threshold is now notexceeded terminating the triggered action; and if the predeterminedthreshold is still exceeded determining whether to at least one oftrigger another action of the plurality of actions, maintain thetriggered action of the plurality of actions, and adjust an aspect ofthe triggered action of the plurality of actions.
 16. The methodaccording to claim 9 wherein, at least one of the first and secondpredetermined standards are selected from the group comprising IEEE802.11, IEEE 802.15, IEEE 802.16, IEEE 802.20, UMTS, GSM 850, GSM 900,GSM 1800, GSM 1900, GPRS, ITU-R 5.138, ITU-R 5.150, ITU-R 5.280, andIMT-2000.
 17. A non-transitory tangible computer readable mediumencoding a computer process for execution by a processor, the computerprocess comprising: (a) determining with the over-the-air measurementblock for each communication session at least one load utilization of aplurality of load utilizations, each load utilization associated with atleast a predetermined traffic class of a plurality of traffic classes;(b) determining with the processor for each traffic class an accumulatedload utilization in dependence upon at least the plurality of loadutilizations relating to the plurality of communication sessionsassociated with that traffic class; (c) determining with the processorwhether a predetermined threshold of a plurality of thresholds has beenexceeded, the predetermined threshold relating to a predeterminedtraffic class; and (d) triggering an action of a plurality of actions bythe load distribution control block when the determination is that apredetermined threshold of the plurality of thresholds has beenexceeded.
 18. The non-transitory tangible computer readable mediumencoding a computer process for execution by a processor according toclaim 17; wherein, triggering an action comprises at least one ofselectively reducing to a first predetermined level the output power ofthe first transmitter beacon transmissions; determining a predeterminedsubset of client stations of the plurality of client stations independence upon at least one of a characteristic of each communicationsession of the plurality of communication sessions and a characteristicof each client station of the plurality of stations; and at least oneselectively reducing to a first predetermined level the output power ofthe first transmitter for transmissions for frames intended only foreach station within the predetermined subset of client stations andsignaling each station within the predetermined subset of clientstations according to a fourth predetermined standard; and determining apredetermined subset of client stations of the plurality of clientstations in dependence upon at least one of a characteristic of eachcommunication session of the plurality of communication sessions and acharacteristic of each client station of the plurality of stations; andterminating the communication sessions associated with the predeterminedsubset of client stations by signaling each client station of thepredetermined subset of client stations according to a fourth standardwith a message to disassociate from the access point.
 19. Thenon-transitory tangible computer readable medium encoding a computerprocess for execution by a processor according to claim 18; wherein, atleast one of a characteristic of each communication session is at leastone of a client station score, a measure of frame transmission rate, ameasure of received signal strength, frame error rate; a characteristicof each client station is at least one of a client station roamingpriority, an identity associated with a client station, and anindication of mobility of a client station; and signaling comprisessignally at least one of an indication of a channel according to thesecond standard for the second device to operate upon, an indication ofan identity of another access device with client station should initiatea second communication session, and an indication for the client stationto invoke a roaming procedure.
 20. The non-transitory tangible computerreadable medium encoding a computer process for execution by a processoraccording to claim 17; wherein, the plurality of client stations form abasic service set (BSS) with the access point or the plurality of clientstations form a BSS with the access point and are one BSS of a pluralityof BSSs supported by the access point, wherein the total availablebandwidth of the access point is partitioned and allocated to theplurality of BSSs according to a predetermined allocation model thatdefines allocations for each traffic class of the plurality of trafficclasses for each BSS of the plurality of BSSs.